Synthesis and biological activity of sulfur compounds showing structural analogy with combretastatin A-4

We extended our previous exploration of sulfur bridges as bioisosteric replacements for atoms forming the bridge between the aromatic rings of combretastatin A-4. Employing coupling reactions between 5-iodo-1,2,3-trimethoxybenzene and substituted thiols, followed by oxidation to sulfones with m-CPBA, different locations for attaching the sulfur atom to ring A through the synthesis of nine compounds were examined. Antitubulin activity was performed with electrophoretically homogenous bovine brain tubulin, and activity occurred with the 1,2,3-trimethoxy-4-[(4-methoxyphenyl)thio]benzene (12), while the other compounds were inactive. The compounds were also tested for leishmanicidal activity using promastigote forms of Leishmania braziliensis (MHOM/BR175/M2904), and the greatest activity was observed with 1,2,3-trimethoxy-4-(phenylthio)benzene (10) and 1,2,3-trimethoxy-4-[(4-methoxyphenyl) sulfinyl]benzene (15).

Flow injection visible diffuse reflectance quantitative analysis of total sulfur in biodiesel, in plant leaves and in natural waters

Flow injection (FI) methodology, using diffuse reflectance in the visible region of the spectrum, for the analysis of total sulfur in the form of sulfate, precipitated in the form of barium sulfate, is presented. The method was applied to biodiesel, to plant leaves and to natural waters analysis. The analytical signal (S) correlates linearly with sulfate concentration (C) between 20 and 120 ppm, through the equation S=-1.138+0.0934 C (r = 0.9993). The experimentally observed limit of detection is about 10 ppm. The mean R.S.D. is about 3.0 %. Real samples containing sulfate were analyzed and the results obtained by the FI and by the reference batch turbidimetric method using the statistical Student's t-test and F-test were compared.

Determination of sulfur in diesel using ATR/FTIR and multivariate calibration

The aim of this present work was to provide a more fast, simple and less expensive to analyze sulfur content in diesel samples than by the standard methods currently used. Thus, samples of diesel fuel with sulfur concentrations varying from 400 and 2500 mgkg-1 were analyzed by two methodologies: X-ray fluorescence, according to ASTM D4294 and by Fourier transform infrared spectrometry (FTIR). The spectral data obtained from FTIR were used to build multivariate calibration models by partial least squares (PLS). Four models were built in three different ways: 1) a model using the full spectra (665 to 4000 cm-1), 2) two models using some specific spectrum regions and 3) a model with variable selected by classic method of variable selection stepwise. The model obtained by variable selection stepwise and the model built with region spectra between 665 and 856 cm-1 and 1145 and 2717 cm-1 showed better results in the determination of sulfur content.

Effect of pulps fractionation on formation and strength properties of laboratory hand sheets

The objectives of the work were to study the effect of dewatering time varying on formation properties of papersheets, to determine the role of fines fraction in creation of paper with good formation and strength properties of papersheets, and also to study the effect of charge modification of fibers fractionations on formation properties of handsheets. The paper formation is one of the most important structural properties of paper. This property has effect on physical and optical characteristics of paper. In thi work the effect of formation on tensile strength was determined. The formation properties were analyzed by using the AMBERTEC Beta Formation Tester. The PAM addition as a f;locculant agent did some changes in the formation of paper. Paper sheets were also made from different furnishes of both birch and pine pulps. The fibers particles as a fines have great effect on drainability changes. Fines fraction played important role in papermaking. The two kinds of pulps (pine and birch pulps) were also used in this work for investigation of fines role. As it was expected the fines fraction gave positive effect on paper formation, but when fines fraction was added above initial fines content the formation of paper was deteriorated. The effect of paper formation on tensile strength was also determined. In many cases the poor formation of paper had negative effect on strength properties of paper..

Fractionation of Hen Egg and Oat Lipids with supercritical Fluids Chemical and functional Properties of Fractions

Hen eggs and oats (Avena Sativa) are important materials for the food industry. Today, instead of merely satisfying the feeling of hunger, consumers are asking for healthier, biologically active and environmentally friendly products. The growing awareness of consumers’ increasing demands presents a great challenge to the food industry to develop more sustainable products and utilise modern and effective techniques. The modification of yolk fatty acid composition by means of feed supplements is well understood. Egg yolk phospholipids are polar lipids and are used in several applications including food, cosmetics, pharmaceuticals, and special nutrients. Egg yolk phospholipids are excellent emulsifiers, typically sold as mixtures of phospholipids, triacylglycerols, and cholesterol. However, highly purified and characterised phospholipids are needed in several sophisticated applications. Industrial fractionation of phospholipids is usually based on organic solvents. With these fractionation techniques, some harmful residues of organic solvents may cause problems in further processing. The objective of the present study was to investigate the methods to improve the functional properties of eggs, to develop techniques to isolate the fractions responsible for the specific functional properties of egg yolk lipids, and to apply the developed techniques to plant-based materials, too. Fractionation techniques based on supercritical fluids were utilised for the separation of the lipid fractions of eggs and oats. The chemical and functional characterisation of the fractions were performed, and the produced oat polar lipid fractions were tested as protective barrier in encapsulation processes. Modifying the fatty acid compositions of egg yolks with different types of oil supplements in feed had no affect on their functional or sensory properties. Based on the results of functional and sensory analysis, it is evident that eggs with modified fatty acid compositions are usable in several industrial applications. These applications include liquid egg yolk products used in mayonnaise and salad dressings. Egg yolk powders were utilised in different kinds of fractionation processes. The precipitation method developed in this study resembles the supercritical anti-solvent method, which is typically used in the pharmaceutical industry. With pilot scale supercritical fluid processes, non-polar lipids and polar lipids were successfully separated from commercially produced egg yolk powder and oat flakes. The egg and oat-based polar lipid fractions showed high purities, and the corresponding delipidated fractions produced using supercritical techniques offer interesting starting materials for the further production of bioactive compounds. The oat polar lipid fraction contained especially digalactosyadiacylglycerol, which was shown to have valuable functional properties in the encapsulation of probiotics.

Biomass fractionation

The objective of this master's thesis was to develop a process to increase the value of residual fungal biomass as an animal feed. The increase in value is achieved by enriching the protein content in the biomass and potentially isolating other valuable fractions for productisation. In the literature part of this thesis the composition of fungal biomass and fungal cell wall and the factors affecting them during cultivation are presented. The possible processing options are also presented and evaluated. The soy protein and single cell protein product manufacturing processes are used as examples due to the lack of fungal biomass fractionation processes found in published literature. The second part of this thesis was performed by making laboratory experiments on the developed process, which consisted of acid hydrolysis with subsequent ethanol extraction. Chitin was precipitated from the acid hydrolysate filtrate. The experiments were conducted with three different hydrolysis temperatures and three different acid concentrations. The optimal hydrolysis conditions were 60 °C with 10 %-vol acid concentration. Optimal conditions in hydrolysis resulted in 30 % increase in protein content in the final biomass. The conceptual process was modelled to scale of 10 000 t/a biomass feed. The mass and energy balances were based on the laboratory experiments. Economic calculations were performed to determine the maximal capital expense while achieving 10 % internal rate of return for the investment. For the basic case the capital expense threshold was 25.8 M€. Four optional cases and parameter sensitivity analysis were performed to determine the effects of changes in the process. The chitin sales had the greatest impact of the individual parameters.

Fate of fuel-bound nitrogen and sulfur in biomass-fired Industrial boilers

Användning av biomassa som energikälla för produktion av el och värme är ett sätt att minska beroendet av fossila bränslen och höja självförsörjningen av energi. Fossila bränslen är den främsta källan till koldioxid utsläpp förorsakad av människan. Biomassa, å andra sidan, betraktas som en koldioxidneutral energikälla. Svavlet och kvävet i biomassan bildar dock föroreningar såsom kväveoxider (NOX) och svaveldioxid (SO2), som bidrar till försurning av mark och sjöar. Svavlet i bränslet kan även både förorsaka och förhindra korrosion i en förbränningsanläggning, beroende på förbränningen och bränslet. Huvudsyftet med detta arbete var att få en bättre förståelse om hur utsläppen av NOX och SO2 bildas från bränslebundet kväve och svavel vid förbränning av olika biobränslen. Mätkampanjer i fullskaliga förbränningsanläggningar utfördes, där gassammansättningen mättes i eldstaden och rökgasen. Förståelsen om gaskemin i eldstaden är viktig, för att möjliggöra utvecklandet av renare och effektivare förbränningsanläggningar. Ett annat syfte med arbetet var att klargöra om sulfatering av askkomponenter vid förbränning av biobränslen med olika askegenskaper. Alkaliklorider som bildas vid biomassaförbränning kan orsaka korrosion av värmeöverföringsytor. Svavlet i bränslet visade sig ha en viktig roll i att sulfatera alkaliklorider till mindre korrosiva alkalisulfater. Närvaron av gasformig svavelsyra i rökgaskanalen av förbränningsanläggningar studerades även. Kondensering av svavelsyra leder till korrosion av rökgaskanalen och dess delar. Om svavelsyrakoncentrationen i rökgasen är känd, kan daggpunktstemperaturen beräknas och kondensering av svavelsyra förhindras. I arbetet utvecklades en mätmetod för att mäta låga koncentrationer av gasformig svavelsyra i rökgaser. Denna metod användes för att undersöka risken av lågtemperaturkorrosion orsakad av svavelsyra i förbränningsanläggningar. ------------------------------------------------------------------------------------------------------------ Käyttämällä biomassaa energianlähteenä voidaan vähentää sähkön- ja lämmöntuotannon riippuvuutta fossiilisiin polttoaineisiin. Biomassan käytöllä voidaan myös lisätä energiantuotannon omavaraisuutta. Fossiiliset polttoaineet ovat pääasiallinen syy ihmisen aiheuttamiin hiilidioksidipäästöihin. Biomassa sen sijaan luetaan hiilidioksidineutraaleihin energianlähteisiin. Biopolttoaineiden käytössä tosin vapautuu typpi- ja rikkioksideja, jotka edesauttavat maaperän ja merien happamoitumista. Lisäksi biopolttoaineen rikki voi sekä vähentää että aiheuttaa laitteiden korroosiota energiantuotannossa riippuen biopolttoaineesta ja palamisesta. Tämän työn päätavoitteena oli selvittää mitä biopolttoaineeseen sitoutuneelle typelle ja rikille tapahtuu teollisissa polttolaitoksissa. Kyseisten oksidien muodostumista tutkittiin polttamalla eri biomassoja polttolaitoksissa. Tutkimukset toteutettiin mittauskampanjoilla useissa polttolaitoksissa. Kaasujen koostumusta mitattiin sekä tulipesässä, että savukaasuista. Kaasujen koostumus varsinkin tulipesässä on tärkeää, jotta tulevaisuudessa voidaan rakentaa puhtaampia ja tehokkaampia polttolaitoksia. Työn toisena tavoitteena oli selvittää biomassan polton yhteydessä tapahtuvaa tuhkan sulfatoitumista. Alkalikloridit, joita muodostuu biomassan poltossa, voivat aiheuttaa lämmönsiirtopintojen korroosiota. Rikki osoittautui tärkeäksi osaksi prosessia, jossa korroosiota aiheuttavat alkalikloridit sulfatoituivat vähemmän korrosoiviksi alkalisulfaateiksi. Myös kaasumaisen rikkihapon läsnäoloa savukaasuissa tutkittiin. On todettu, että kaasumuotoinen rikkihappo johtaa korroosioon savukaasukanavan kylmässä päässä ja sen eri osissa rikkihapon tiivistyessä lämpötilan laskiessa. Mikäli rikkihapon pitoisuus savukaasussa tiedetään, sen kastepiste voidaan laskea ja tiivistyminen estää. Tässä työssä kehitettiin mittausmenetelmä rikkihapon alhaisten pitoisuuksien mittaamiseen. Menetelmää hyödynnettiin polttolaitoksissa, joissa tutkittiin rikkihapon tiivistymisestä johtuvaa korroosiota.

Towards optimal fractionation of lignocellulosic biomass using switchable ionic liquids

En ny familj av reversibla (switchable) joniska vätskor (SIL) innehållande 1,8-diazobicyklo-[5.4.0]-undek-7-en (DBU), en molekyl innehållande en eller flera hydroxyl- grupper (t.ex. glycerol) och en sur gas (CO2, SO2) syntetiserades via en enkel procedur samt karakteriserades. [DBU][karbonat] eller [sulfonat] bildades ur en respektive icke-jonisk blandning av en molekylär, organisk polyol (eller ennan molekyl innehållande en OH-grupp) och en amidinbas under bubblandet av en sur gas. Därtill kunde den joniska vätskan omvandlas tillbaka till sina beståndsdelar med hjälp av att upphetta och/eller bubbla en inert gas såsom kväve genom vätskan. SIL- strukturerna kartlades med bl.a. NMR- och FTIR- spektroskopi. Omvandlingen från lågpolära (molekylära) vätskor till högpolära joniska vätskor (SIL) bekräftades även genom att observera förändringar i deras fysikaliska egenskaper, såsom viskositet och färg. Nedbrytningstemperaturerna hos SILs bestämdes med hjälp av termogravimetrisk analys (TGA) som antydde att nedbrytningstemperaturen hos de syntetiserade föreningarna log mellan 50 och 200oC. De nya joniska vätskorna uppvisade högre nedbrytningstemperaturer jämfört med i litteraturen tidigare förekommande exempel och kunde därför tillämpas på flera ändamål. Därtill, reversibla (switchable) joniska vätskor uppbyggda av bl.a. alkoholer, antingen hexanol eller butanol, och CO2 samt en amidin (DBU) användes vid upplösning och fraktionering av ved. Joniska vätskor syntetiserade ur glycerol och sura gaser tillsammans med amidiner användes även för fraktionering av andra lignocellulosor såsom färsk björk (Betula pendula). Björkflis utsattes för behandling, för en period på en till fem dagar vid 100oC och under atmosfäriskt tryck. Alla syntetiserade joniska vätskor visade sig vara relativt neutrala i avseende på upplösning och avlägsnandet av lignin. Slutligen, optimala fraktioneringprocessbetingelser för ved med reversibla joniska vätskor kartlades. Fraktionering av vedbiomassa med dessa joniska vätskor uppvisade sig att vara en selektiv och effektiv metod för extraktion av olika komponenter från lignocellulosa. Den olösta fraktionen hos en vedflis, närmast cellulosa, fibrillerades. -------------------------------------------------------------------------------------------------------------------- Tässä työssä kehitettiin perhe uuden tyyppisiä, reversiibeleitä (switchable) ioninesteitä ( SIL ) joka koostuvat orgaanisesta super-emäksestä kuten 1,8- diatsabisyklo [ 5.4.0] undek- 7-eeni (DBU ) ja yhden tai useampia hydroksyyliryhmiä sisältältävästä molekyylistä (esim. glyseroli) ja happamasta kaasusta (CO2 , SO2) yksinkertaisen menetelmän avulla. [DBU] [ karbonaatti] tai [sulfonaatti] syntetisoitiin kunkin lähtöaineen seoksista kuplittamalla seosta happamalla kaasulla jolloin eksoterminen reaktio tapahtui ja ioninen neste syntyi. Ioniset nesteet voitiin palauttaa takaisin lähtöaineseokseksi kuumentamalla ja/tai kuplittamalla neutraalia kaasua (esim. typpi) seoksen läpi. SIL rakenteet määritettiin ja niiden ominaisuudet kartoitettiin eri menetelmillä, mukaan lukien NMR- ja FTIR -spektroskopia. Ionisen, korkeapoläärisen nesteen syntyminen todennettiin myös viskositeettimittauksilla ja värinmuutoksilla käyttäen hyväksi polariteetti-indikaattoria (Nile red). Myös hajoamislämpötilat määritettiin termogravimetrisellä analyysillä (TGA) ja todettiin että syntetisoitujen yhdisteiden hajoamislämpötila oli välillä 50 ja 200oC . Näiden uusien reversiibeleiden ioninesteiden hajoamisämpötilat olivat korkeammat verrattuna kirjallisuudessa aikaisemmin mainittuihin esimerkkeihin joten niitä voidaan soveltaa useisiin tarkoituksiin. Myös ioninesteitä jotka sisälsivät primäärejä alkoholeja rakennusaineina syntetisoitiin ja hyödynnettiin puun fraktioinnissa. Männyn ja kuusen lisäksi tuoreita koivulastuja onnistuttiin fraktioimaan miedoissa olosuhteissa. Kaikkien syntetisoitujen ioninesteiden todettiin olevan suhteellisen neutraaleja ligniinin liuotuksen suhteen. Vielä, optimaaliset fraktiointiolosuhteet määritettiin ryhmälle reversiibeleitä ioninesteitä ja näiden uudenlaisten ioninesteiden todettiin olevan tehokkaita puun ja muiden lignoselluloosien eri fraktioiden liuotuksessa. Liukenematon osa puulastua joka oli lähinnä selluloosaa fibrilloitui.

Association of sulfur dioxide exposure with circulatory system deaths in a medium-sized city in Brazil

There is a demonstrable association between exposure to air pollutants and deaths due to cardiovascular diseases. The objective of this study was to estimate the effects of exposure to sulfur dioxide on mortality due to circulatory diseases in individuals 50 years of age or older residing in São José dos Campos, SP. This was a time-series ecological study for the years 2003 to 2007 using information on deaths due to circulatory disease obtained from Datasus reports. Data on daily levels of pollutants, particulate matter, sulfur dioxide (SO2), ozone, temperature, and humidity were obtained from the São Paulo State Environmental Agency. Moving average models for 2 to 7 days were calculated by Poisson regression using the R software. Exposure to SO2 was analyzed using a unipollutant, bipollutant or multipollutant model adjusted for mean temperature and humidity. The relative risks with 95%CI were obtained and the percent decrease in risk was calculated. There were 1928 deaths with a daily mean (± SD) of 1.05 ± 1.03 (range: 0-6). Exposure to SO2 was significantly associated with mortality due to circulatory disease: RR = 1.04 (95%CI = 1.01 to 1.06) in the 7-day moving average, after adjusting for ozone. There was an 8.5% decrease in risk in the multipollutant model, proportional to a decrease of SO2 concentrations. The results of this study suggest that residents of medium-sized Brazilian cities with characteristics similar to those of São José dos Campos probably have health problems due to exposure to air pollutants.

Sugar fractionation and pectin content during the ripening of guava cv. Pedro Sato

Guava is one of the most complete and balanced fruits in in terms of s nutritional value. Highly perishable, due to its intense metabolism during ripening, its shelf life can reach 3 to 5 days under room temperature. The firmness of the green and mature fruits is due mainly to the pectin polymers. The loss of firmness during the guava ripening is due to hydrolytic enzyme activity, which promotes intense solubilization of the cell wall pectins. Given the above, with the purpose of trying to explain the rapid firmness decrease, the centesimal composition and sugar fraction of the guava fruit were determined during ripening at room temperature. The guavas were picked at the half-mature stage and stored for 8 days at 22 ± 1 ºC and 78 ± 1% relative humidity. The analyses conducted were: centesimal composition, sugar fractionation, and infrared absorption spectrometry. The results showed that the guava sugars did not vary during ripening. The estimated pectin levels (5.7%) were higher than those mentioned in the literature (2.4%), which can better explain the role of the pectin in the fruit firmness.

Influence of distillation time and sample mass on sulfur dioxide analysis in passion fruit juice through Monier-Williams method

AbstractThis study aimed to evaluate the effect of the distillation time and the sample mass on the total SO2 content in integral passion fruit juice (Passiflora sp). For the SO2 analysis, a modified version of the Monier-Williams method was used. In this experiment, the distillation time and the sample mass were reduced to half of the values proposed in the original method. The analyses were performed in triplicate for each distilling time x sample mass binomial, making a total of 12 tests, which were performed on the same day. The significance of the effects of the different distillation times and sample mass were evaluated by applying one-factor analysis of variance (ANOVA). For a 95% confidence limit, it was found that the proposed amendments to the distillation time, sample mass, and the interaction between distilling time x sample mass were not significant (p > 0.05) in determining the SO2 content in passion fruit juice. In view of the results that were obtained it was concluded that for integral passion fruit juice it was possible to reduce the distillation time and the sample mass in determining the SO2 content by the Monier-Williams method without affecting the result.

Chemical changes in biomass during torrefaction

Torrefaction is moderate thermal treatment (~200-300 °C) of biomass in an inert atmosphere. The torrefied fuel offers advantages to traditional biomass, such as higher heating value, reduced hydrophilic nature, increased its resistance to biological decay, and improved grindability. These factors could, for instance, lead to better handling and storage of biomass and increased use of biomass in pulverized combustors. In this work, we look at several aspects of changes in the biomass during torrefaction. We investigate the fate of carboxylic groups during torrefaction and its dependency to equilibrium moisture content. The changes in the wood components including carbohydrates, lignin, extractable materials and ashforming matters are also studied. And at last, the effect of K on torrefaction is investigated and then modeled. In biomass, carboxylic sites are partially responsible for its hydrophilic characteristic. These sites are degraded to varying extents during torrefaction. In this work, methylene blue sorption and potentiometric titration were applied to measure the concentration of carboxylic groups in torrefied spruce wood. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic group contents. Thus, both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction. This provides new information to the chemical changes occurring during torrefaction. The effect of torrefaction temperature on the chemistry of birch wood was investigated. The samples were from a pilot plant at Energy research Center of the Netherlands (ECN). And in that way they were representative of industrially produced samples. Sugar analysis was applied to analyze the hemicellulose and cellulose content during torrefaction. The results show a significant degradation of hemicellulose already at 240 °C, while cellulose degradation becomes significant above 270 °C torrefaction. Several methods including Klason lignin method, solid state NMR and Py-GC-MS analyses were applied to measure the changes in lignin during torrefaction. The changes in the ratio of phenyl, guaiacyl and syringyl units show that lignin degrades already at 240 °C to a small extent. To investigate the changes in the extractives from acetone extraction during torrefaction, gravimetric method, HP-SEC and GC-FID followed by GC-MS analysis were performed. The content of acetone-extractable material increases already at 240 °C torrefaction through the degradation of carbohydrate and lignin. The molecular weight of the acetone-extractable material decreases with increasing the torrefaction temperature. The formation of some valuable materials like syringaresinol or vanillin is also observed which is important from biorefinery perspective. To investigate the change in the chemical association of ash-forming elements in birch wood during torrefaction, chemical fractionation was performed on the original and torrefied birch samples. These results give a first understanding of the changes in the association of ashforming elements during torrefaction. The most significant changes can be seen in the distribution of calcium, magnesium and manganese, with some change in water solubility seen in potassium. These changes may in part be due to the destruction of carboxylic groups. In addition to some changes in water and acid solubility of phosphorous, a clear decrease in the concentration of both chlorine and sulfur was observed. This would be a significant additional benefit for the combustion of torrefied biomass. Another objective of this work is studying the impact of organically bound K, Na, Ca and Mn on mass loss of biomass during torrefaction. These elements were of interest because they have been shown to be catalytically active in solid fuels during pyrolysis and/or gasification. The biomasses were first acid washed to remove the ash-forming matters and then organic sites were doped with K, Na, Ca or Mn. The results show that K and Na bound to organic sites can significantly increase the mass loss during torrefaction. It is also seen that Mn bound to organic sites increases the mass loss and Ca addition does not influence the mass loss rate on torrefaction. This increase in mass loss during torrefaction with alkali addition is unlike what has been found in the case of pyrolysis where alkali addition resulted in a reduced mass loss. These results are important for the future operation of torrefaction plants, which will likely be designed to handle various biomasses with significantly different contents of K. The results imply that shorter retention times are possible for high K-containing biomasses. The mass loss of spruce wood with different content of K was modeled using a two-step reaction model based on four kinetic rate constants. The results show that it is possible to model the mass loss of spruce wood doped with different levels of K using the same activation energies but different pre-exponential factors for the rate constants. Three of the pre-exponential factors increased linearly with increasing K content, while one of the preexponential factors decreased with increasing K content. Therefore, a new torrefaction model was formulated using the hemicellulose and cellulose content and K content. The new torrefaction model was validated against the mass loss during the torrefaction of aspen, miscanthus, straw and bark. There is good agreement between the model and the experimental data for the other biomasses, except bark. For bark, the mass loss of acetone extractable material is also needed to be taken into account. The new model can describe the kinetics of mass loss during torrefaction of different types of biomass. This is important for considering fuel flexibility in torrefaction plants.

Fractionation, chemical and toxicological characterization of tobacco smoke components

La fumée du tabac est un aérosol extrêmement complexe constitué de milliers de composés répartis entre la phase particulaire et la phase vapeur. Il a été démontré que les effets toxicologiques de cette fumée sont associés aux composés appartenant aux deux phases. Plusieurs composés biologiquement actifs ont été identifiés dans la fumée du tabac; cependant, il n’y a pas d’études démontrant la relation entre les réponses biologiques obtenues via les tests in vitro ou in vivo et les composés présents dans la fumée entière du tabac. Le but de la présente recherche est de développer des méthodes fiables et robustes de fractionnement de la fumée à l’aide de techniques de séparation analytique et de techniques de détection combinés à des essais in vitro toxicologiques. Une étude antérieure réalisée par nos collaborateurs a démontré que, suite à l’étude des produits de combustion de douze principaux composés du tabac, l’acide chlorogénique s’est avéré être le composé le plus cytotoxique selon les test in vitro du micronoyau. Ainsi, dans cette étude, une méthode par chromatographie préparative en phase liquide a été développée dans le but de fractionner les produits de combustion de l’acide chlorogénique. Les fractions des produits de combustion de l’acide chlorogénique ont ensuite été testées et les composés responsables de la toxicité de l’acide chlorogénique ont été identifiés. Le composé de la sous-fraction responsable en majeure partie de la cytoxicité a été identifié comme étant le catéchol, lequel fut confirmé par chromatographie en phase liquide/ spectrométrie de masse à temps de vol. Des études récentes ont démontré les effets toxicologiques de la fumée entière du tabac et l’implication spécifique de la phase vapeur. C’est pourquoi notre travail a ensuite été focalisé principalement à l’analyse de la fumée entière. La machine à fumer Borgwaldt RM20S® utilisée avec les chambres d’exposition cellulaire de British American Tobacco permettent l’étude in vitro de l’exposition de cellules à différentes concentrations de fumée entière du tabac. Les essais biologiques in vitro ont un degré élevé de variabilité, ainsi, il faut prendre en compte toutes les autres sources de variabilité pour évaluer avec précision la finalité toxicologique de ces essais; toutefois, la fiabilité de la génération de la fumée de la machine n’a jamais été évaluée jusqu’à maintenant. Nous avons donc déterminé la fiabilité de la génération et de la dilution (RSD entre 0,7 et 12 %) de la fumée en quantifiant la présence de deux gaz de référence (le CH4 par détection à ionisation de flamme et le CO par absorption infrarouge) et d’un composé de la phase particulaire, le solanesol (par chromatographie en phase liquide à haute performance). Ensuite, la relation entre la dose et la dilution des composés de la phase vapeur retrouvée dans la chambre d’exposition cellulaire a été caractérisée en utilisant une nouvelle technique d’extraction dite par HSSE (Headspace Stir Bar Sorptive Extraction) couplée à la chromatographie en phase liquide/ spectrométrie de masse. La répétabilité de la méthode a donné une valeur de RSD se situant entre 10 et 13 % pour cinq des composés de référence identifiés dans la phase vapeur de la fumée de cigarette. La réponse offrant la surface maximale d’aire sous la courbe a été obtenue en utilisant les conditions expérimentales suivantes : intervalle de temps d’exposition/ désorption de 10 0.5 min, température de désorption de 200°C pour 2 min et température de concentration cryogénique (cryofocussing) de -75°C. La précision de la dilution de la fumée est linéaire et est fonction de l’abondance des analytes ainsi que de la concentration (RSD de 6,2 à 17,2 %) avec des quantités de 6 à 450 ng pour les composés de référence. Ces résultats démontrent que la machine à fumer Borgwaldt RM20S® est un outil fiable pour générer et acheminer de façon répétitive et linéaire la fumée de cigarette aux cultures cellulaires in vitro. Notre approche consiste en l’élaboration d’une méthodologie permettant de travailler avec un composé unique du tabac, pouvant être appliqué à des échantillons plus complexes par la suite ; ex : la phase vapeur de la fumée de cigarette. La méthodologie ainsi développée peut potentiellement servir de méthode de standardisation pour l’évaluation d’instruments ou de l’identification de produits dans l’industrie de tabac.