Determination of formaldehyde and acetaldehyde levels in poly(ethylene terephthalate) (PET) bottled mineral water using a simple and rapid analytical method.

A simple and rapid analytical method was developed for the determination of formaldehyde (FA) and acetaldehyde (AA) contents in water. FA and AA were derivatized by 2,4-dinitrophenylhydrazine in an LC vial for 20 min at room temperature, about 25 °C, and analyzed using LC-MS/MS. The calibration curve exhibited excellent linearity for FA and AA concentrations of 2-150 ng/mL. Recovery tests using ultra-pure water and commercially available PET-bottled mineral water samples showed good trueness and precision. We determined the FA and AA contents in 105 PET-bottled mineral water samples on the Japanese market using this method. FA was detected in 61% of the samples at levels from 2.6 to 31.4 ng/mL, while AA was detected in 68% at levels from 5.3 to 143.5 ng/mL. These results demonstrate that the concentrations of FA and AA in PET-bottled mineral water on the Japanese market have not changed significantly over the last decade.

Determination of malondialdehyde, acrolein and four other products of lipid peroxidation in edible oils by Gas-Diffusion Microextraction combined with Dispersive Liquid-Liquid Microextraction.

A new and sensitive analytical method for the simultaneous determination of secondary lipid peroxidation aldehydes has been successfully developed and validated. Malondialdehyde, acrolein, formaldehyde, acetaldehyde, propanal, and pentanal were extracted and derivatized using 2,4-dinitrophenylhydrazine (DNPH) by gas-diffusion microextraction (GDME) combined with dispersive liquid-liquid microextraction (DLLME) for gas chromatography-mass spectrometry (GC-MS) analysis. The experimental conditions have been optimized by experimental designs. The analytical method validation, in accordance to the Food and Drug Administration (FDA) guidance, provided good results in terms of linearity with r2≥0.9974, in the range from 0.15 or 0.3 µg·g-1 to 3 µg·g-1. Limits of detection and limits of quantification were 0.05 or 0.10 and 0.15 or 0.3 µg·g-1, respectively. Precision was tested as a relative standard deviation (RSD≤ 9.5%) and recoveries were between 95% and 110%. The method was applied in the characterization of aldehydes in forty-eight edible oil samples; with the highest concentration found in pomace olive oil for malondialdehyde at 6.64 µg·g-1.

Identification of the Volatile Components of Galium verum L. and Cruciata leavipes Opiz from the Western Italian Alps.

The chemical composition of the volatile fraction from Galium verum L. (leaves and flowers) and Cruciata laevipes Opiz (whole plant), Rubiaceae, was investigated. Samples from these two plant species were collected at full bloom in Val di Susa (Western Alps, Turin, Italy), distilled in a Clevenger-type apparatus, and analyzed by GC/FID and GC/MS. A total of more than 70 compounds were identified, making up 92%-98% of the total oil. Chemical investigation of their essential oils indicated a quite different composition between G. verum and C. laevipes, both in terms of the major constituents and the dominant chemical classes of the specialized metabolites. The most abundant compounds identified in the essential oils from G. verum were 2-methylbenzaldheyde (26.27%, corresponding to 11.59 µg/g of fresh plant material) in the leaves and germacrene D (27.70%; 61.63 µg/g) in the flowers. C. laevipes essential oils were instead characterized by two sesquiterpenes, namely ß-caryophyllene (19.90%; 15.68 µg/g) and trans-muurola-4(15),5-diene (7.60%; 5.99 µg/g); two phenylpropanoids, benzyl alcohol (8.30%; 6.71 µg/g), and phenylacetaldehyde (7.74%; 6.26 µg/g); and the green-leaf alcohol cis-3-hexen-1-ol (9.69%; 7.84 µg/g). The ecological significance of the presence of such compounds is discussed.

Identification and Characterization of Nematicidal Volatile Organic Compounds from Deep-Sea Virgibacillus dokdonensis MCCC 1A00493.

Root-knot nematode diseases cause severe yield and economic losses each year in global agricultural production. Virgibacillus dokdonensis MCCC 1A00493, a deep-sea bacterium, shows a significant nematicidal activity against Meloidogyne incognita in vitro. However, information about the active substances of V. dokdonensis MCCC 1A00493 is limited. In this study, volatile organic compounds (VOCs) from V. dokdonensis MCCC 1A00493 were isolated and analyzed through solid-phase microextraction and gas chromatography-mass spectrometry. Four VOCs, namely, acetaldehyde, dimethyl disulfide, ethylbenzene, and 2-butanone, were identified, and their nematicidal activities were evaluated. The four VOCs had a variety of active modes on M. incognita juveniles. Acetaldehyde had direct contact killing, fumigation, and attraction activities; dimethyl disulfide had direct contact killing and attraction activities; ethylbenzene had an attraction activity; and 2-butanone had a repellent activity. Only acetaldehyde had a fumigant activity to inhibit egg hatching. Combining this fumigant activity against eggs and juveniles could be an effective strategy to control the different developmental stages of M. incognita. The combination of direct contact and attraction activities could also establish trapping and killing strategies against root-knot nematodes. Considering all nematicidal modes or strategies, we could use V. dokdonensis MCCC 1A00493 to set up an integrated strategy to control root-knot nematodes.

Biofiltration of acetaldehyde resulting from ethanol manufacturing facilities.

At ethanol plants, the control of acetaldehyde emissions is accomplished by scrubbers and regenerative thermal oxidizers. However, their operation imposes substantial operating costs. Alternatively, two biotrickling filters were operated in parallel under acetaldehyde loadings ranging from 4 to 136 g m-3 hr-1. One filter was operated at room temperature while the other one was heated to 60 °C, to mimic hot drier emissions. The unheated filter maintained 100% removal efficiency up to 45.28 g m-3 hr-1 loading rate at 30-s empty bed residence time. Highest elimination capacity recorded was 112 g m-3 hr-1 at 83.2% removal efficiency. The heated filter achieved removal efficiency larger than 60% at influent concentrations of 200 ppmv and lower, however, removal was significantly lower at 400 and 600 ppmv influent concentrations. Performance was improved by reseeding with cooking compost resulting in increased thermophilic bacterial population. Main byproduct formed was acetic acid with traces of formic acid. Mathematical modelling was used to successfully describe acetaldehyde concentration profiles.

Protective Effects of Facilitated Removal of Blood Alcohol and Acetaldehyde Against Liver Injury in Animal Models Fed Alcohol and Anti-HIV Drugs.

BACKGROUND: We previously developed enzyme nanoparticles (ENP) of alcohol metabolism. This study was to evaluate protective effects of facilitated removal of blood alcohol and/or acetaldehyde on anti-HIV drugs and alcohol-induced liver injuries. METHODS: ENP were prepared for degrading alcohol completely (ENP1) or partially into acetaldehyde (ENP2), which were applied to mice of acute binge or chronic-binge alcohol feeding in the presence of antivirals (ritonavir and lopinavir). Liver pathologies were examined to assess the protective effects of ENP. RESULTS: In the acute model, ENP1 and ENP2 reduced the blood alcohol concentration (BAC) by 41 and 32%, respectively, within 4 hr, whereas in control without ENP, BAC was reduced only by 15%. Blood acetaldehyde concentration (BADC) was increased by 39% in alcohol-fed mice treated with ENP2 comparing to control. No significant effects of the anti-HIV drugs on BAC or BADC were observed. Plasma alanine aminotransferase (ALT) and expression of liver TNF-α were both significantly increased in the alcohol-fed mice, which were normalized by ENP1. In the presence of the antivirals, ALT was partially reduced by ENP1 or ENP2. In the chronic model, inflammation, fatty liver, and ALT were increased, which were deteriorated by the antivirals. ENP1 partially reduced BAC, BADC, ALT, and expression of inflammation markers of TNF-α, F4/80, and IL-6 and lipogenic factors of ACC, LXRα, and SREBP1. ENP2 reduced BAC without significant effects on ALT, inflammation, or lipogenesis. Antivirals and alcohol synergistically increased expression of organelle stress markers of CHOP, sXBP-1, ATF6, and GCP60. ENP1 reduced BAC, CHOP, and sXbp-1. However, no effects of ENP1 were found on ATF6 or GCP60. CONCLUSIONS: Removal of blood alcohol and acetaldehyde by the ENP protects the liver against alcoholic injuries, and the protection is less effective in chronic alcohol and antiviral feeding due to additional drug-induced organelle stresses.

Volatile organic compounds of Thai honeys produced from several floral sources by different honey bee species.

The volatile organic compounds (VOCs) of four monofloral and one multifloral of Thai honeys produced by Apis cerana, Apis dorsata and Apis mellifera were analyzed by headspace solid-phase microextraction (HS-SPME) followed by gas chromatography and mass spectrometry (GC-MS). The floral sources were longan, sunflower, coffee, wild flowers (wild) and lychee. Honey originating from longan had more VOCs than all other floral sources. Sunflower honey had the least numbers of VOCs. cis-Linalool oxide, trans-linalool oxide, ho-trienol, and furan-2,5-dicarbaldehyde were present in all the honeys studied, independent of their floral origin. Interestingly, 2-phenylacetaldehyde was detected in all honey sample except longan honey produced by A. cerana. Thirty-two VOCs were identified as possible floral markers. After validating differences in honey volatiles from different floral sources and honeybee species, the results suggest that differences in quality and quantity of honey volatiles are influenced by both floral source and honeybee species. The group of honey volatiles detected from A. cerana was completely different from those of A. mellifera and A. dorsata. VOCs could therefore be applied as chemical markers of honeys and may reflect preferences of shared floral sources amongst different honeybee species.

Isotopic separation of acetaldehyde and methanol from their deuterated isotopologues on a porous layer open tubular column allows quantification by stable isotope dilution without mass spectrometric detection.

An isotopic separation of acetaldehyde and acetaldehyde-2,2,2-d3 was achieved in a temperature programmed run on a porous layer open tubular (PLOT) capillary column coated with particles of divinylbenzene ethylene glycol/dimethylacrylate (Rt®-U-BOND). This is the prerequisite for the development of quantitative analytical methods based on a stable isotope dilution assay (SIDA) without a mass spectrometric detection (non-MS SIDA). For routine analysis a flame ionization detector (FID) can thus be applied as a robust and low-cost alternative. In a preliminary study, static headspace extraction and gas chromatographic separation (HS-GC-FID) of acetaldehyde in aqueous solutions was shown as an application. Good linearity was obtained in a calibration range from 0.4 to 40mgL-1, with peak integration benefitting from the inverse isotope effect encountered on the specific porous polymer. Furthermore, separation of methanol and deuterated methanol (d3) could also be achieved under the same chromatographic conditions. The achieved isotopic separation of these important volatile compounds now allows non-MS SIDA-based methods that are still to be developed.

Chemical Compositions and Aroma Evaluation of Volatile Oil from the Industrial Cultivation Medium of Enterococcus faecalis.

Enterococcus faecalis is one of the major lactic acid bacterium (LAB) species colonizing the intestines of animals and humans. The characteristic odor of the volatile oils obtained from both the liquid medium after incubation (MAI) and liquid medium before incubation (MBI) in the cultivation process of E. faecalis was investigated to determine the utility of the liquid medium. In total, fifty-six and thirty-two compounds were detected in the volatile oils from the MAI (MAI oil) and MBI (MBI oil), respectively. The principle components of MAI oil were 2,5-dimethylpyrazine (19.3%), phenylacetaldehyde (19.3%), and phenylethyl alcohol (9.3%). The aroma extract dilution analysis (AEDA) method was performed using gas chromatography-olfactometry (GC-O). The total number of aroma-active compounds identified in the volatile oil from MBI and MAI was thirteen compounds; in particular, 5-methyl-2-furanmethanol, phenylacetaldehyde, and phenylethyl alcohol were the most primary aroma-active compounds in MAI oil. These results imply that the industrial cultivation medium after incubation of E. faecalis may be utilized as a source of volatile oils.

Characteristic Chemical Components and Aroma-active Compounds of the Essential Oils from Ranunculus nipponicus var. submersus Used in Japanese Traditional Food.

Ranunculus nipponicus var. submersus is an aquatic macrophyte; it is known as a wild edible plant in Japan for a long time. In this study, the essential oils from the fresh and dried aerial parts of R. nipponicus var. submersus were extracted by hydrodistillation and analyzed by gas chromatography (GC) and GC-mass spectrometry (GC-MS). Moreover, important aroma-active compounds were also detected in the oil using GC-olfactometry (GC-O) and aroma extract dilution analysis (AEDA). Thus, 98 compounds (accounting for 93.86%) of the oil were identified. The major compounds in fresh plant oil were phytol (41.94%), heptadecane (5.92%), and geranyl propionate (5.76%), while those of. Dried plant oil were ß-ionone (23.54%), 2-hexenal (8.75%), and dihydrobovolide (4.81%). The fresh and dried oils had the green-floral and citrus-floral odor, respectively. The GC-O and AEDA results show that phenylacetaldehyde (green, floral odor, FD-factor = 8) and ß-ionone (violet-floral odor, FD-factor = 8) were the most characteristic odor compounds of the fresh oils. ß-Cyclocitral (citrus odor, FD-factor = 64) and ß-ionone (violet-floral odor, FD-factor = 64) were the most characteristic odor compounds of the dried oil. These compounds are thought to contribute to the flavor of R. nipponicus var. submersus.

Isolation and expression of NAC genes during persimmon fruit postharvest astringency removal.

NAC genes have been characterized in numerous plants, where they are involved in responses to biotic and abiotic stress, including low oxygen stress. High concentration of CO2 is one of the most effective treatments to remove astringency of persimmon fruit owing to the action of the accumulated anoxia metabolite acetaldehyde. In model plants, NAC genes have been identified as being responsive to low oxygen. However, the possible relationship between NAC transcription factors and persimmon astringency removal remains unexplored. In the present research, treatment with a high concentration of CO2 (95%) effectively removed astringency of "Mopan" persimmon fruit by causing decreases in soluble tannin. Acetaldehyde content increased in response to CO2 treatment concomitantly with astringency removal. Using RNA-seq and Rapid amplification of cDNA ends (RACE), six DkNAC genes were isolated and studied. Transcriptional analysis indicated DkNAC genes responded differentially to CO2 treatment; DkNAC1, DkNAC3, DkNAC5 and DkNAC6 were transiently up-regulated, DkNAC2 was abundantly expressed 3 days after treatment, while the DkNAC4 was suppressed during astringency removal. It is proposed that DkNAC1/3/5/6 could be important candidates as regulators of persimmon astringency removal and the roles of other member are also discussed.

Acetaldehyde removal using an atmospheric non-thermal plasma combined with a packed bed: role of the adsorption process.

This work is an attempt in order to help towards understanding the influence of the adsorption process on the removal of a VOC (acetaldehyde, CH3CHO) using cyclic non thermal plasma (NTP) combined with a packed-bed of a catalyst support, α-Al2O3. In the first part, the results obtained by placing the saturated alumina pellets inside the plasma discharge zone are discussed, in terms of acetaldehyde removal, CO and CO2 production. In the second part, adsorption of CH3CHO, CO, CO2 and O3 was carried out, from single and multicomponent mixtures of the different compounds. The results showed that (i) the adsorption capacities followed the order CH3CHO≫ CO2>CO; (ii) O3 was decomposed on the alumina surface; (iii) CO oxidation occurred on the surface when O3 was present. In the third part, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to follow the alumina surface during acetaldehyde adsorption. DRIFTS measurements demonstrated that besides the bands of molecularly adsorbed acetaldehyde, several absorptions appeared on the spectra showing the intermediate surface transformation of acetaldehyde already at 300K. Finally, the relationship between the adsorption results and the NTP combined with a packed-bed process is discussed.

Characterization of volatile components and odor-active compounds in the oil of edible mushroom Boletopsis leucomelas.

The volatile oil from Boletopsis leucomelas (Pers.) Fayod was extracted by hydrodistillation with diethylether, and the volatile components of the oil were analyzed by gas chromatography-mass spectrometry. The oil contained 86 components, representing 87.5% of the total oil. The main components of the oil were linoleic acid (15.0%), phenylacetaldehyde (11.2%), and palmitic acid (9.4%). Furthermore, sulfur-containing compounds including 3-thiophenecarboxaldehyde, 2-acetylthiazole, S-methyl methanethiosulfonate, and benzothiazole were detected using gas chromatography-pulsed flame photometric detection. The odor components were evaluated by the odor activity value, and aroma extract dilution analysis was performed through gas chromatography-olfactometry analysis. The oil had a mushroom-like, fatty, and burnt odor. The main components contributing to the mushroom-like and fatty odor were hexanal, nonanal, 1-octen-3-ol, and (2E)-nonenal, while the burnt odor was due to furfuryl alcohol, benzaldehyde, 5-methyl furfural, 2,3,5-trimethylpyrazine, 2-acethylthiazole, and indole.

Circadian release of male-specific components of the greater date moth, Aphomia (Arenipses) sabella, using sequential SPME/GC/MS analysis.

The greater date moth (GDM), Aphomia sabella Hampson (Lepidoptera: Pyralidae: Galleriinae), is a serious pest of date palms, Phoenix dactylifera. The release of volatiles from both males and females was investigated using sequential SPME/GC/MS analysis. Males release a complex mixture of compounds in a circadian rhythm during the night between 03:00 and 05:00 hr. Six compounds were identified: benzaldehyde, sulcatol (6-methyl-5-hepten-2-ol), geranyl acetone [(E)-6,10-dimethyl-5,9-undecadien-2-one], phenylacetaldehyde, 2-phenylpropenal, and (R)-fuscumol [(R)-(E)-6, 10-dimethyl-5, 9-undecadien-2-ol]. Benzaldehyde, sulcatol, and geranyl acetone were found only in trace amounts. These compounds were in glands located in the forewing of males only. Small amounts of acetoin and 2,3-butanediol were found sporadically in the SPME/GC/MS analyses of volatiles from females, and these compounds probably originate from microorganisms. This is the first finding of a circadian release of male-specific compounds in moths. GC/EAD analyses with synthetic standards of compounds released by males showed that the female antenna is stimulated by all six compounds, while the male antenna responded only to phenylacetaldehyde. A possible pheromonal role for the male-specific compounds is suggested by the circadian rhythm of their release and the EAD response of females to them. However, trapping tests with the main male-specific compounds in screen cages in the laboratory or in the field did not reveal any significant behavioral responses from females or males. Copulation in the laboratory was observed only in the presence of date palm tissue, thus suggesting that sexual communication and mating of GDM moths probably occurs in the crown of date palms.

Characterization of aroma-active compounds in dry flower of Malva sylvestris L. by GC-MS-O analysis and OAV calculations.

In this study, the aroma-active compounds in the dried flower of Malva sylvestris L. were extracted by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), and gas chromatography-olfactometry (GC-O) and aroma extraction dilution analysis (AEDA). A light yellow oil with a sweet odor was obtained with a percentage yield of 0.039% (w/w), and 143 volatile compounds (89.86%) were identified by GC-MS. The main compounds were hexadecanoic acid (10.1%), pentacosane (4.8%) and 6,10,14-trimethyl-2-pentadecanone (4.1%). The essential oil consisted mainly of hydrocarbons (25.40%) followed by, alcohols (18.78%), acids (16.66%), ethers (5.01%) ketones (7.28%), esters(12.43%), aldehydes (2.30%) and others (2.00%). Of these compounds, 20 were determined by GC-O and AEDA, to be odor-active (FD (flavor dilution) factor ≥ 1). ß-Damascenone (FD = 9, sweet), phenylacetaldehyde (FD = 8, floral, honey-like) and (E)-ß-ocimene (FD = 8, spicy) were the most intense aroma-active compounds in M. sylvestris. In order to determine the relative contribution of each of the compounds to the aroma of M. sylvestris, odor activity values (OAVs) were used. ß-Damascenone had the highest odor activity values (OAV) (50,700), followed by (E)-ß-ionone (15,444) and decanal (3,510). In particular, ß-damascenone had a high FD factors, and therefore, this compound was considered to be the main aroma-active components of the essential oil. On the basis of AEDA, OAVs, and sensory evaluation results, ß-damascenone is estimated to be the main aroma-active compound of the essential oil.

Evaluation of a UV-light emitting diodes unit for the removal of micropollutants in water for low energy advanced oxidation processes.

There is growing interest in using light emitting diodes (LEDs) as alternative to traditional mercury lamps for the removal of micropollutants by advanced oxidation processes due to their low energy consumption and potential for high efficiency and long lifetime. This study investigates the penetration and coverage of the light emitted by LEDs in order to build an optimised LED collimated beam apparatus. From the experimental data, cost analysis was conducted in order to identify when LEDs will become economically viable. It was observed that if their development follows the predictions, LEDs should be a viable alternative to traditional lamps within 7yr for both UV/H2O2 and UV/TiO2 processes. However, parameters such as wall plug efficiency and input power need to improve for LEDs to become competitive.

Evaluation of different derivatisation approaches for gas chromatographic-mass spectrometric analysis of carbohydrates in complex matrices of biological and synthetic origin.

Gas chromatographic analysis of complex carbohydrate mixtures requires highly effective and reliable derivatisation strategies for successful separation, identification, and quantitation of all constituents. Different single-step (per-trimethylsilylation, isopropylidenation) and two-step approaches (ethoximation-trimethylsilylation, ethoximation-trifluoroacetylation, benzoximation-trimethylsilylation, benzoximation-trifluoroacetylation) have been comprehensively studied with regard to chromatographic characteristics, informational value of mass spectra, ease of peak assignment, robustness toward matrix effects, and quantitation using a set of reference compounds that comprise eight monosaccharides (C(5)-C(6)), glycolaldehyde, and dihydroxyacetone. It has been shown that isopropylidenation and the two oximation-trifluoroacetylation approaches are least suitable for complex carbohydrate matrices. Whereas the former is limited to compounds that contain vicinal dihydroxy moieties in cis configuration, the latter two methods are sensitive to traces of trifluoroacetic acid which strongly supports decomposition of ketohexoses. It has been demonstrated for two "real" carbohydrate-rich matrices of biological and synthetic origin, respectively, that two-step ethoximation-trimethylsilylation is superior to other approaches due to the low number of peaks obtained per carbohydrate, good peak separation performance, structural information of mass spectra, low limits of detection and quantitation, minor relative standard deviations, and low sensitivity toward matrix effects.

Catalytic removal of acetaldehyde in saliva by a Gluconobacter strain.

Acetaldehyde (AA) accumulates in the oral cavity after alcohol intake and is responsible for an increased risk of alcohol-related upper aerodigestive tract (UDAT) cancer among aldehyde dehydrogenase 2-inactive heterozygotes in particular. Thus, the removal of AA from the saliva to a level below its mutagenic concentration (50 µM) after drinking is a potentially straightforward method for reducing the risk of alcohol-related UDAT cancer. Although microbial cells with AA-decomposing activity could potentially serve as a useful agent for the catalytic removal of AA from the saliva without the supplemental addition of cofactors, these cells generally exhibit strong AA-producing activity from ethanol, which is present in excess (50mM) over AA (100 µM) in the saliva after drinking. In this study, we observed that Gluconobacter kondonii (GK) cells efficiently decomposed salivary AA (100-390 µM) without the supplemental addition of cofactors irrespective of the type of alcoholic beverages consumed, even in the presence of an excess of ethanol (63 mM). Hydrogen peroxide, which is carcinogenic in animal experiments, was not produced because of the AA removal. The GK cells incubated at 45 °C and pH 3.5 for 15 h were killed, but they retained 80% of their original AA-decomposing activity. The treated cells were used as nonviable microcapsules that harbor a membrane-bound AA-decomposing activity.

Mineralization of gaseous acetaldehyde by electrochemically generated Co(III) in H2SO4 with wet scrubber combinatorial system.

Electrochemically generated Co(III) mediated catalytic room temperature incineration of acetaldehyde, which is one of volatile organic compounds (VOCs), combined with wet scrubbing system was developed and investigated. Depending on the electrolyte's type, absorption come removal efficiency is varied. In presence of electrogenerated Co(III) in sulfuric acid, acetaldehyde was mineralized to CO2 and not like only absorption in pure sulfuric acid. The Co(III) mediated catalytic incineration led to oxidative absorption and elimination to CO2, which was evidenced with titration, CO2, and cyclic voltammetric analyses. Experimental conditions, such as current density, concentration of mediator, and gas molar flow rate were optimized. By the optimization of the experimental conditions, the complete mineralization of acetaldehyde was realized at a room temperature using electrochemically generated Co(III) with wet scrubber combinatorial system.

Application of gas-diffusion microextraction to the analysis of free and bound acetaldehyde in wines by HPLC-UV and characterization of the extracted compounds by MS/MS detection.

In wines, the presence of high levels of acetaldehyde (AA) not only is responsible for undesirable characteristic odours but can also cause health adverse effects. Such sensorial activity of AA can be overcome by adding sulphites during winemaking, due to the formation of adducts between AA and sulphites, which lower the sensorial impact of AA. Nevertheless, bound AA can be released during wine storage; therefore, the knowledge of its total amount can be important to estimate the long-term wine quality. The proposed methodology is based on the extraction of AA from wines using gas-diffusion microextraction and determination by liquid chromatography. Free and bound forms of AA could be differentiated and determined using an alkaline hydrolysis step to dissociate the sulphites-AA adducts. This methodology was successfully applied to different wine types, with free AA values ranging between 5 and 26 mg L(-1) and total form between 154 and 906 mg L(-1). Bound AA was above 90% of the total content determined for all samples analysed, and higher amounts were obtained for white wines (around 98%). Other carbonyl compounds were also identified in the extracts using mass spectrometry.