Aldehydes In Gas Phase Research Articles

Gas Phase Aldehydes Detection in Exhaled Breath in Screening of Barrett's Esophagus

Aldehydes, e.g., acetaldehyde, have been classified as toxic and carcinogenic volatile organic compounds (VOCs) and are recognized as one determinant of upper aerodigestive tract cancer like Barrett's esophagus. Measuring aldehyde levels in breath provides information about the aldehydes released by abnormal cells, the level of aldehyde dehydrogenase (ALDH2) activity, and risks and diseases associated with high levels of acetaldehyde, which include liver disease and lung and upper digestive cancers. Devices currently available for breath analysis are state-of-the-art, high-resolution mass spectrometry instruments. These instruments have some drawbacks such as size, initial cost, and operational expense. Electrochemical sensors are capable of miniaturization and are available as portable and handheld breathalyzers. The non-invasive nature of breath analysis and its easy sampling makes smaller devices a more attractive alternative, particularly for continuous monitoring and point-of-care (POC) testing.1 However, the lack of an exchangeable/disposable sensing element, the resulting memory effect, and the need for frequent recalibration is the main drawback of currently available electrochemical breathalyzers.Herein we examine the feasibility of a POC testing device for aldehyde in exhaled breath to assess the medical application of such a device in noninvasive diagnostic testing for Barrett’s esophagus. To improve the selectivity of the method we harness the unique catalytic activity of the aminoxyl radical/oxoammonium redox couple toward aldehyde oxidation. The highly selective/sensitive device offers the capability for use in the detection of Barrett's esophagus, ideally at early stages, without the need for a high-cost screening test. Our functional sensing element consists of a screen-printed electrode (SPE) in which the graphene oxide-based is the working electrode. Exposing this electrode to simulated breath that contains aldehyde, while applying the required potential for oxidation of the aminoxyl radical (4-acetamido-TEMPO known as ACT), generates an electrocatalytic current proportional to the aldehyde concentration in the breath. These simple, sensitive, durable, and inexpensive electrodes may contribute to the development of a single-use reliable aldehyde sensor for personal or law enforcement applications.1. M. Mayer, M. Rafiee, Electrocatalytic Detection of Ethanol and Acetaldehyde by Aminoxyl Radicals: Utilizing Molecular Catalysis for Breath Analysis. Analyst 147, 2022, 3420 – 3423.

Comprehensive Analysis of Products and the Development of a Quantitative Mechanism for the OH Radical-Initiated Oxidation of 1-Alkenes in the Presence of NOx.

The reactions of 1-tetradecene and 1-pentadecene, the C14 and C15 linear 1-alkenes, with OH radicals in the presence of NOx were investigated in a series of environmental chamber experiments. Particle-phase β-hydroxynitrates, dihydroxynitrates, dihydroxycarbonyls, and 1,4-hydroxynitrates and gas-phase aldehydes were sampled and then identified and quantified using a suite of offline analytical techniques that included derivatization, gas and liquid chromatography, and multiple types of mass spectrometry. Measured molar yields of products formed by OH radical addition to the C═C double bond, including β-hydroxynitrates, dihydroxynitrates, dihydroxycarbonyls (which have not been previously directly quantified with high accuracy), and aldehydes were 0.125 ± 0.01, 0.048 ± 0.005, 0.240 ± 0.04, and 0.268 ± 0.03 (0.264 ± 0.02 and 0.271 ± 0.04 for the formaldehyde and tridecanal/tetradecanal co-products of β-hydroxyalkoxy radical decomposition), respectively. These values give a total molar yield of 0.681 ± 0.05, which agrees very well with the results of kinetics measurements that indicate that the fraction of reaction that occurs by OH radical addition is 0.70. The yields were used to calculate branching ratios for all OH radical addition pathways, including a value of 0.18 for the formation of dihydroxynitrates from the reaction of dihydroxyperoxy radicals with NO and values of 0.47 and 0.53 for β-hydroxyalkoxy radical decomposition and isomerization. The results were used with literature data on the yields of aldehydes measured for similar reactions of smaller alkenes, a model for the effect of carbon number on branching ratios for organic nitrate formation, and a mechanism for H atom abstraction derived from studies of linear alkanes to achieve a complete, quantitative gas-phase reaction mechanism for 1-alkenes. The results should also be useful for constructing mechanisms for more complex reactions of volatile organic compounds.

Point-of-Care Test Paper for Exhaled Breath Aldehyde Analysis via Mass Spectrometry.

Volatile organic compounds (VOCs) from exhaled breath (EB) are considered to be promising biomarkers for lung diseases. A convenient and sensitive point-of-care (POC) testing method for EB VOCs is essential. Here, we developed a POC test paper for the analysis of EB aldehydes, which are potential biomarkers for lung cancer. A probe molecule, 4-aminothiophenol (4-ATP), was anchored on a paper substrate to specifically capture gas-phase aldehydes through the Schiff base reaction. Meanwhile, thin-film reaction acceleration was utilized to increase capture efficiency. By directly coupling the test paper to a mass spectrometer through paper spray, high sensitivity (0.1 ppt) and a wide quantification linear range (from 10 ppt to 1 ppm) were obtained. Analysis of EB from lung cancer patients with the test paper showed a significant increase in several reported aldehyde markers compared to EB from healthy volunteers, indicating the potential of this method for sensitive, low-cost, and convenient lung cancer screening and diagnosis.

Simultaneous Determination of Four Aldehydes in Gas Phase of Mainstream Smoke by Headspace Gas Chromatography-Mass Spectrometry.

A method for simultaneous determination of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde in gas phase of cigarette mainstream smoke by headspace gas chromatography-mass spectrometry was developed and validated. Gas phase components of mainstream cigarette smoke were extracted with methanol, and then the samples were separated on a DB 624 (60 m, 0.32 mm x 1.8 mm) column, analyzed with headspace gas chromatography-mass spectrometry, and quantified by isotope internal standard. The linearities of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde were good (R2>0.992). The recoveries of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde were between 78.5% and 115%. The relative standard deviations were less than 10%. The limits of detection and limits of quantitation were 0.014 μg/cigarette ~0.12 μg/cigarette and 0.045 μg/cigarette ~0.38 μg/cigarette, respectively. The method had advantage of high sensitivity, it did not require derivatization of 2,4-dinitrophenylhydrazine and avoided a large number of adverse reactions during the process of derivation to improve the accuracy of result, and it was suitable for quantitative analysis of four aldehydes in gas phase of cigarette mainstream smoke.

Two new alkaline earth metal organic frameworks with the diamino derivative of biphenyl-4,4′-dicarboxylate as bridging ligand: Structures, fluorescence and quenching by gas phase aldehydes

Alkaline earth metal ion organic frameworks (AEMOFs) represent a relatively underexplored subcategory of MOFs. Two new MOFs [Ca6(bpdc-(NH2)2)5(μ3-HCO2)2(H2O)2.5(DMF)0.5]·0.5H2O·2.5DMF (1) and [Sr4(bpdc-(NH2)4)(μ2-DMF)2(DMF)1/3]·2/3(DMF) (2) [H2bpdc-(NH2)2 = 2,2′-diamino-[1,1′-biphenyl]-4,4′-dicarboxylic acid); DMF = N,N-dimethylformamide] are presented here. These MOFs display structural variety with diverse topologies and new structural features. Luminescence studies revealed that both MOFs display ligand based fluorescence with small differences in emission profiles possibly attributable to the difference in charge density of the metal ions combined with the different conformation adopted by the ligand in the crystal structures of 1 and 2. Furthermore, initial sensing studies reveal that both MOFs can potentially function as fluorescent sensors for gas phase aldehydes.

Formation of gas-phase carbonyls from heterogeneous oxidation of polyunsaturated fatty acids at the air–water interface and of the sea surface microlayer

Abstract. Motivated by the potential for reactive heterogeneous chemistry occurring at the ocean surface, gas-phase products were observed when a reactive sea surface microlayer (SML) component, i.e. the polyunsaturated fatty acids (PUFA) linoleic acid (LA), was exposed to gas-phase ozone at the air–seawater interface. Similar oxidation experiments were conducted with SML samples collected from two different oceanic locations, in the eastern equatorial Pacific Ocean and from the west coast of Canada. Online proton-transfer-reaction mass spectrometry (PTR-MS) University of Colorado light-emitting diode cavity-enhanced differential optical absorption spectroscopy (LED-CE-DOAS) were used to detect oxygenated gas-phase products from the ozonolysis reactions. The LA studies indicate that oxidation of a PUFA monolayer on seawater gives rise to prompt and efficient formation of gas-phase aldehydes. The products are formed via the decomposition of primary ozonides which form upon the initial reaction of ozone with the carbon–carbon double bonds in the PUFA molecules. In addition, two highly reactive dicarbonyls, malondialdehyde (MDA) and glyoxal, were also generated, likely as secondary products. Specific yields relative to reactant loss were 78%, 29%, 4% and < 1% for n-hexanal, 3-nonenal, MDA and glyoxal, respectively, where the yields for MDA and glyoxal are likely lower limits. Heterogeneous oxidation of SML samples confirm for the first time that similar carbonyl products are formed via ozonolysis of environmental samples.

Facile Synthesis of Phosphate-Functionalized MWCNT-TiO2 Nanocomposites as Efficient Photocatalysts and Insights into the Roles of Nanostructured Carbon.

Effectively contacted multiwalled carbon nanotube (MWCNT)-titanium dioxide nanocomposites and phosphate-functionalized MWCNT-TiO2 composites have been successfully synthesized by simple one-pot phase-separated hydrolysis-solvothermal processes. The key to this synthetic strategy is to disperse MWCNTs uniformly in Ti(OBu)4 in advance and then to put them into the toluene organic phase. The as-prepared nanocomposites between TiO2 and the correct amount of MWCNT exhibits higher activity in the photocatalytic degradation of rhodamine B than that with the resulting TiO2 , although the activity in the photocatalytic degradation of gas-phase aldehyde and liquid-phase phenol is lower. Interestingly, the functionalization of MWCNTs with an appropriate amount of phosphoric acids prior to the synthesis could greatly improve the activity of the MWCNT-TiO2 nanocomposites for the degradation of aldehyde and phenol, even superior to that of commercial P25 TiO2 . Based on the measurements of atmosphere-controlled surface photovoltage spectra and O2 temperature-programmed desorption, it is suggested that MWCNTs are favorable to increase rhodamine B adsorption on the composite to promote the photosensitization oxidation reactions, whereas it is unfavorable for the adsorption of O2 and responsible for the low photocatalytic activity for the degradation of colorless pollutants. Phosphate functionalization greatly enhances the amount of O2 adsorbed on the MWCNT, which leads to significant charge separation, and thus, to significant photoactivity for the degradation of colored and colorless pollutants of the nanocomposites.

Synthesis of Efficient Nanosized Rutile TiO2 and Its Main Factors Determining Its Photodegradation Activity: Roles of Residual Chloride and Adsorbed Oxygen

Nanosized TiO2 containing different contents of rutile phase was controllably synthesized by a hydrochloric acid-modified hydrothermal process. It is demonstrated that the formation of rutile phase in TiO2 mainly depends on the role of chlorine anions in the synthesis, and a certain amount of residual chloride would exist on the surfaces of the resulting nanocrystalline rutile TiO2. Interestingly, the as-prepared rutile shows high activity for photodegradation of rhodamine B dye compared with the as-prepared anatase, even superior to the P25 TiO2. It is mainly attributed to the residual chloride that could promote the dye adsorbed on the surfaces of TiO2, consequently accelerating the photosensitization oxidation reactions of the dye molecules. In the photodegradation of liquid-phase phenol and gas-phase aldehyde, the as-prepared rutile TiO2 samples display low activity, which is attributed to the photogenerated electrons weakly captured by the adsorbed oxygen, since the residual chloride could effectively capture photoinduced holes based on the atmosphere-controlled surface photovoltage spectroscopy results. Further, the photoactivity of resulting rutile for degrading phenol and aldehyde is greatly enhanced by modifying a proper amount of phosphoric acids to increase the adsorption of O2, even higher than that of the P25 TiO2. This work would explore feasible routes to synthesize efficient nanosized rutile TiO2-based photocatalysts for degrading colored and colorless organic pollutants by investigating the rate-determining factors in the photodegradation processes.

Mechanism of the catalytic gas-phase aldehyde production from trinuclear W 3S 4 complexes bearing W-OEt groups

Collision induced dissociation experiments of the alkoxo [W 3S 4(dmpe) 2(O)(OCH 2CH 3)] + tungsten (IV) cation reveal that aldehyde elimination is the dominant reaction pathway. Complementary deuterium labelling experiments give support to a hydrogen transfer mechanism, where the hydrogen atom exclusively originates from the α-position of the alkoxo ligand. On the basis of DFT calculations, two competitive mechanisms are proposed: one of them involving a proton transfer from the α-position of the alkoxo ligand to an oxygen atom of the vicinal W O group; the other corresponding to a hydride transfer mechanism from the α-position of the alkoxo ligand to the geminate tungsten center. The calculated energy profiles show that the former is thermodynamically favoured and the second is kinetically favoured, with small energy differences between the two reaction paths; in consequence, both mechanisms compete under our experimental conditions. The proton transfer mechanism occurs through a seven-membered transition state structure while hydride transfer takes place through a four-center structure defined by the metal and the oxygen, carbon and hydrogen atoms of the ethoxo group.

Atmospheric Secondary Aerosol Formation by Heterogeneous Reactions of Aldehydes in the Presence of a Sulfuric Acid Aerosol Catalyst

Particle growth by the heterogeneous reaction of aldehydes was evaluated in 0.5 m3 Teflon film bags under darkness in the presence of background seed aerosols. The aldehydes used were as follows: glyoxal, butanal, hexanal, octanal, and decanal. To study acid catalyst effects on aldehyde heterogeneous reactions, one of the Teflon bags was initially filled with seed aerosols composed of ammonium sulfate-aerosol acidified with sulfuric acid. These results were compared to particle growth reactions that contained only ammonium sulfate as a background seed aerosol. The gas-phase aldehydes were then added to the Teflon bags. In selected experiments, 1-decanol was also added to the Teflon bags with aldehydes to clarify particle growth via a heterogeneous hemiacetal/acetal formation in the presence/absence of an acid catalyst. The particle size distribution and growth were measured using a scanning mobility particle sizer (TSI-SMPS), and the results were applied to predicting aerosol growth and size distribution changes by condensation and heterogeneous reactions. Aerosols created from the heterogeneous reactions of aldehydes were collected directly on an ungreased zinc selenide (ZnSe) FTIR disk (25 mm in diameter) by impaction. The ZnSe disks were directly analyzed for product functional groups inthe aerosol phase using a Fourier transform infrared (FTIR) spectrometer with a deuterated triglycine sulfate (DTGS) detector. Aerosol growth by heterogeneous aldehyde reactions proceeds via a hydration, polymerization process, and hemiacetal/acetal formation from the reaction of aldehydes with alcohols. These aldehyde heterogeneous reactions were accelerated in the presence of an acid catalyst, H2SO4, and led to higher aerosol yields than when H2SO4 was not present in the seed aerosol. The FTIR spectra obtained from the growing aerosol, also illustrated aldehyde group transformation in the particle phase as a function of the heterogeneous reaction. It was concluded that aldehydes, which can be produced by atmospheric photochemical reactions, can significantly contribute on secondary aerosol formation through heterogeneous reactions in the presence of an acid catalyst.

Selective detection of gas-phase aldehydes and ketones using protonated hydrazine

This article reports the results of the gas phase studies of protonated hydrazine, N2H5+, reactions with different classes of organic compounds in a chemical ionization mass spectrometer (CIMS). We found that saturated aldehydes react with N2H5+, in the presence of a drift field and neutral hydrazine, to form primarily a protonated hydrazone, e.g. formaldehyde reacts to form CH2N2H3+. Unsaturated aldehydes, saturated ketones, and hydroxyl substituted carbonyl compounds react to form protonated hydrazones and association complexes, e.g. N2H5+ · acetone. In the absence of a drift field, methanol, ethanol, and toluene react to form association complexes; otherwise, no reaction occurs. We propose a method of detecting gas-phase aldehydes and ketones using protonated hydrazine, N2H5+, as a reagent ion in a CIMS. The method was demonstrated by measuring three C6 aldehydes released by grass that had been frozen, crushed and thawed. Qualitatively and quantitatively, the results compare favorably with the results of aldehyde emission experiments reported by others.

Airborne Aldehydes from Heating Rosin Core Solder and Liquid Rosin Flux to Soldering Temperatures

Gas phase aldehydes produced from heating rosin core solder and liquid rosin flux to temperatures commonly used in soldering were trapped on sampling tubes containing XAD-2 resin coated with the derivatizing agent 2-hydroxymethylpiperidine. Analysis of the resulting oxazolidine derivatives was performed using gas chromatography/mass spectrometry (GC/MS). The observed aldehyde derivatives included formaldehyde, acetaldehyde, propionaldehyde, acrolein, isobutyraldehyde, butyraldehyde, isovaleraldehyde, valeraldehyde, furfural, hexanal, cyclohexane carboxaldehyde and other unidentified compounds likely to be aldehyde isomers. Formaldehyde, acetaldehyde, and benzaldehyde were detected in blank samples. By comparison with an internal standard, a sample produced by drawing air with contaminants derived by heating rosin core solder through a sampling tube contained levels of formaldehyde and acetaldehyde much greater than seen in sampling tube blanks. Benzaldehyde was not shown to be present at a significantly greater level in samples from heating rosin core solder than in blanks prepared using the same analysis protocol. The use of National Institute of Occupational Safety and Health (NIOSH) method 2539 extraction procedures produced blanks with levels of formaldehyde significantly lower than with a modified extraction method (methylene chloride, no sonication). The modified extraction method produced significantly lower benzaldehyde levels in blanks compared with the NIOSH extraction method using toluene and sonication of sampling sorbent tubes.

Airborne Aldehydes from Heating Rosin Core Solder and Liquid Rosin Flux to Soldering Temperatures

Gas phase aldehydes produced from heating rosin core solder and liquid rosin flux to temperatures commonly used in soldering were trapped on sampling tubes containing XAD-2 resin coated with the derivatizing agent 2-hydroxymethylpiperidine. Analysis of the resulting oxazolidine derivatives was performed using gas chromatography/mass spectrometry (GC/MS). The observed aldehyde derivatives included formaldehyde, acetaldehyde, propionaldehyde, acrolein, isobutyraldehyde, butyraldehyde, isovaleraldehyde, valeraldehyde, furfural, hexanal, cyclohexane carboxaldehyde and other unidentified compounds likely to be aldehyde isomers. Formaldehyde, acetaldehyde, and benzaldehyde were detected in blank samples. By comparison with an internal standard, a sample produced by drawing air with contaminants derived by heating rosin core solder through a sampling tube contained levels of formaldehyde and acetaldehyde much greater than seen in sampling tube blanks. Benzaldehyde was not shown to be present at a significantly greater level in samples from heating rosin core solder than in blanks prepared using the same analysis protocol. The use of National Institute of Occupational Safety and Health (NIOSH) method 2539 extraction procedures produced blanks with levels of formaldehyde significantly lower than with a modified extraction method (methylene chloride, no sonication). The modified extraction method produced significantly lower benzaldehyde levels in blanks compared with the NIOSH extraction method using toluene and sonication of sampling sorbent tubes.

Multistep collisionally activated decomposition in an ion trap for the determination of the amino-acid sequence and gas-phase ion chemistry of lithium-coordinated valinomycin

Evidence from collisionally activated decomposition (CAD) of electrospray-produced ions in an ion trap shows that lithium ion binds to the backbone ester oxygen atoms of valinomycin to open the cyclodepsipeptide ring at the D-α-hydroxyvaleric acid and L-lactic acid residues. The two resulting ring-opened, linear acylium ions are sequenced by multiple stages (up to MS 10) of CAD. Amino-acid residues are sequentially cleaved from the acylium terminus of the peptides, one amino-acid residue at each stage of the CAD experiment, until each acylium ion is converted to a tripeptide species at MS 10. This method builds upon a previously published strategy for determining the amino-acid sequences of cyclic peptides and is used here for the valinomycin-based class of ionophore antibiotics. This entirely instrumental approach overcomes ambiguities encountered in assigning amino-acid sequences of cyclic peptides by other tandem mass spectrometric methods. These ambiguities arise from indiscriminate and multiple ring-opening reactions that occur during collisional activation of cyclic peptides, resulting in tandem mass spectra that are superpositions of random fragment ions. Multiple stages of CAD in an ion trap also facilitate more accurate interpretation of the tandem mass spectra of valinomycin [M + Li] + by unambiguously revealing the genealogies of the fragment ions. Furthermore, it reveals new gas-phase aldehyde elimination, proton transfer, and intramolecular ion rearrangement reactions that occur upon collisional activation of valinomycin [M + Li] +. Cyclic peptides produce b n ions upon ring opening and fragmentation. Therefore, they may serve as models for understanding the mechanisms of linear peptide fragmentation.

Formation and Thermal Decomposition of Butyl-Substituted Peroxyacyl Nitrates: n-C4H9C(O)OONO2 and i-C4H9C(O)OONO2

The butyl-substituted peroxyacyl nitrates n-C 4 H 9 C(O)-OONO 2 and i-C 4 H 9 C(O)OONO 2 have been synthesized in the liquid phase, prepared in-situ in the gas phase by sunlight irradiation of aldehyde-NO mixtures, measured by electron capture gas chromatography, and characterized in a number of gas-phase and liquid-phase tests. Gas-phase yields as a fraction of initial NO were 0.39 for the n-butyl isomer and 0.20 for the isobutyl isomer. The corresponding gas-phase aldehyde oxidation mechanisms are outlined. Thermal decomposition in the presence of excess NO yielded n-butanal and isobutanal as the major carbonyl products.(...)

Uptake of gas-phase aldehydes by water surfaces

The uptake of gas-phase formaldehyde and acetaldehyde by water droplets was measured along with mass accomodation coefficients. Formaldehyde uptake is predictable, but that of acetaldehyde as short gas-droplet contact times is greater than predicted due to a chemisorbed surface complex at the gas-water interface that may explain the high measured concentration of acetaldehyde in clouds relative to formaldehyde. The small uptake coefficients suggest that this may be the limiting factor in aldehyde uptake into clouds. 36 refs., 10 figs., 3 tabs.

POTASSIUM AND MAGNESIUM NUTRITION EFFECTS ON YIELD AND CHEMICAL COMPOSITION OF BURLEY TOBACCO LEAVES AND SMOKE

A field experiment was conducted to determine the effects of varying levels of K and Mg fertilization on the yield, value, and chemical composition of burley tobacco (Nicotiana tabacum L. cv. Ky-14) leaves and smoke. Potassium was applied at rates of 0,112, 224, and 448 kg K/ha as K2SO4 and KNO3, and Mg was applied at rates of 0, 56, 112 and 224 kg Mg/ha as MgO. Potassium fertilization (112 kg K/ha) increased the cured leaf yield and its market value about 12% over the control. Additional increases in market value were observed where 224 and 448 kg K/ha were applied. Magnesium did not significantly affect leaf yield and market value; there was no Mg × K interaction for these characters. Potassium fertilization reduced protein-N, total volatile nitrogenous bases (TVNB), amino-N, Ca, and Mg contents of leaf by 12, 10, 25, 23, and 32%, respectively, from the control when applied at the rate of 448 kg K/ha. In contrast, K fertilization increased leaf K and Mn contents 5.6- and 1.2-fold, respectively. Magnesium application depressed leaf amino-N content and increased Mg content. Total particulate matter (TPM), nicotine, and gas phase cyanide delivered from all-burley cigarettes were decreased by 24, 7, and 50% from the control when plots were supplied with 448 kg K/ha. However, the gas phase aldehyde content of the smoke was increased by K application. Magnesium fertilization had no measurable effects on the chemical composition of burley tobacco smoke.

A Trapping System for the Combined Determination of Total HCN and Total Gas Phase Aldehydes in Cigarette Smoke

AbstractA procedure for the combined determination of total HCN and total gas phase aldehydes in cigarette smoke has been developed which is practical to use for the analysis of relatively large cigarette samples. The smoking system includes a Cambridge pad for collection of the particulate phase and a small tube of silica gel to trap gas phase components, with 5 cigarettes being smoked through each pad and trap. Following smoking, the Cambridge pad and silica gel trap are extracted; the silica gel extract is used for the determination of total gas phase aldehydes and the combined extracts for HCN analysis. Colourimetric procedures, automated through use of the Technicon AutoAnalyser as described previously, are employed for the analysis of the sample extracts. Evaluation of this combined procedure indicates that it yields reliable results for both total HCN and total gas phase aldehydes with greater speed and ease of operation than provided by the previously described methods. The procedure has been applied to various cigarette samples with the relative standard deviation for a single port of 5 cigarettes ranging from 1.9 to 5.5 % for gas phase aldehydes and from 2.6 to 8.4 % for total HCN.