Analysis of flavor formation during the production of Jinhua dry-cured ham using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS).

This study aimed to clarify the formation process of flavor compounds and identify the volatile substances present during a continuous period of Jinhua dry-cured ham (JDH) making. Via headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), a total of 53 volatile organic compounds (VOCs), including 20 aldehydes, 16 alcohols, 11 ketones, 5 esters and 1 furan, were identified in JDH from seven sampling stages. The results showed that butanal, 3-methylbutanal, 2-methylbutanal, 2-hexanone, 2-pentanone and 2-butanone could be flavor markers in the evolution of aroma characteristics of JDH. Aldehydes (2-methylbutanal and 3-methylbutanal), alcohols (2-methylpropanol, 2-methylbutanol, 3-methylbutanol and 1-penten-3-ol), ketones (2-pentanone, 2-propanone, 2-butanone and 2-hexanone) and esters (ethyl acetate and ethyl 3-methylbutyrate) were considered the main VOCs in the mature JDH. Free fatty acid (FFA) analysis displayed the changes in intramuscular fat (IMF) of JDH. Additionally, principal component analysis (PCA) showed that drying-ripening was a critical stage in the flavor formation of JDH.

Identification of a non-host semiochemical from miniature pinscher, Canis lupus familiaris, that repels Rhipicephalus sanguineus sensu lato (Acari: Ixodidae).

It is already known that the beagle breed of domestic dogs produces semiochemicals capable of repelling the brown dog tick, Rhipicephalus sanguineus sensu lato (s.l.). With a view to discovering new non-host semiochemicals as tick repellents, we compared the semiochemicals produced by a putative tick-resistant breed of dog, miniature pinscher, with known tick-resistant (beagle) and tick-susceptible (English cocker spaniel) breeds. Two non-host compounds produced by beagles, i.e. 2-hexanone and benzaldehyde, were shown to be present in samples collected from all three breeds. Furthermore, two compounds, 6-methyl-5-hepten-2-one and 1,2,4-trimethylbenzene, were found in higher amounts in samples collected from miniature pinscher dogs. The mean amounts of benzaldehyde, 2-hexanone and 1,2,4-trimethylbenzene were similar for beagles and miniature pinschers (P > 0.05) and higher than the means observed for cocker spaniels (P < 0.05), whereas the mean amount of 6-methyl-5-hepten-2-one produced by miniature pinschers was significantly higher (P < 0.05) than for the other breeds of dogs. In Petri-dish assays with adult R. sanguineus s.l., 6-methyl-5-hepten-2-one was repellent for all observation periods evaluated for the two highest concentrations (0.100 and 0.200 mg.cm-2, P < 0.01). The obtained results support our hypothesis that miniature pinschers are a tick-resistant dog breed and agree with previous observations of miniature pinschers being the breed least parasitized by ticks. Furthermore, the non-host semiochemical 6-methyl-5-hepten-2-one has potential to be developed for use as a repellent for the protection of susceptible dogs from R. sanguineus s.l. ticks.

Machine Vision Methods, Natural Language Processing, and Machine Learning Algorithms for Automated Dispersion Plot Analysis and Chemical Identification from Complex Mixtures.

Gas-phase trace chemical detection techniques such as ion mobility spectrometry (IMS) and differential mobility spectrometry (DMS) can be used in many settings, such as evaluating the health condition of patients or detecting explosives at airports. These devices separate chemical compounds in a mixture and provide information to identify specific chemical species of interest. Further, these types of devices operate well in both controlled lab environments and in-field applications. Frequently, the commercial versions of these devices are highly tailored for niche applications (e.g., explosives detection) because of the difficulty involved in reconfiguring instrumentation hardware and data analysis software algorithms. In order for researchers to quickly adapt these tools for new purposes and broader panels of chemical targets, it is critical to develop new algorithms and methods for generating libraries of these sensor responses. Microelectromechanical system (MEMS) technology has been used to fabricate DMS devices that miniaturize the platforms for easier deployment; however, concurrent advances in advanced data analytics are lagging. DMS generates complex three-dimensional dispersion plots for both positive and negative ions in a mixture. Although simple spectra of single chemicals are straightforward to interpret (both visually and via algorithms), it is exceedingly challenging to interpret dispersion plots from complex mixtures with many chemical constituents. This study uses image processing and computer vision steps to automatically identify features from DMS dispersion plots. We used the bag-of-words approach adapted from natural language processing and information retrieval to cluster and organize these features. Finally, a support vector machine (SVM) learning algorithm was trained using these features in order to detect and classify specific compounds in these represented conceptualized data outputs. Using this approach, we successfully maintain a high level of correct chemical identification, even when a gas mixture increases in complexity with interfering chemicals present.

Quantification of brown dog tick repellents, 2-hexanone and benzaldehyde, and release from tick-resistant beagles, Canis lupus familiaris.

We have recently shown that repellency of the tick Rhipicephalus sanguineus sensu lato by the tick resistant dog breed, the beagle, is mediated by volatile organic compounds (VOCs) 2-hexanone and benzaldehyde present in beagle odour. Ectoparasite location of animal hosts is affected by variation in these odour components and their ratios. The aim of this study was to quantify the release rate, and the ratio, of 2-hexanone and benzaldehyde from beagles. The odour of three beagles was collected, for four days, over one week (day 0, day 1, day 4 and day 7). The compounds were identified using coupled high-resolution gas chromatography-mass spectrometry (GC-MS), and authentic standards of compounds were used to generate external calibration curves for quantification. Both compounds were found in all dogs on all days. The amount of benzaldehyde was always higher than that of 2-hexanone and so their ratio varied from unity, on average (over time) being 3.128±0.365, 1.902±0.390, 1.670±0.671ngmL(-1) for beagle 1, 2 and 3, respectively. There was no significant (p<0.05, F-test) effect of time. The overall mean was 2.233±0.387ngmL(-1). These results further previous findings by documenting the presence of 2-hexanone and benzaldehyde in beagle odour samples covering a 7-day period. This knowledge enables development of repellents to protect dogs from R. sanguineus s. l. infestation.

Hexavalent chromium and isocyanate exposures during military aircraft painting under crossflow ventilation.

Exposure control systems performance was investigated in an aircraft painting hangar. The ability of the ventilation system and respiratory protection program to limit worker exposures was examined through air sampling during painting of F/A-18C/D strike fighter aircraft, in four field surveys. Air velocities were measured across the supply filter, exhaust filter, and hangar midplane under crossflow ventilation. Air sampling conducted during painting process phases (wipe-down, primer spraying, and topcoat spraying) encompassed volatile organic compounds, total particulate matter, Cr[VI], metals, nitroethane, and hexamethylene diisocyanate, for two worker groups: sprayers and sprayer helpers ("hosemen"). One of six methyl ethyl ketone and two of six methyl isobutyl ketone samples exceeded the short term exposure limits of 300 and 75 ppm, with means 57 ppm and 63 ppm, respectively. All 12 Cr[VI] 8-hr time-weighted averages exceeded the recommended exposure limit of 1 µg/m3, 11 out of 12 exceeded the permissible exposure limit of 5 µg/m3, and 7 out of 12 exceeded the threshold limit value of 10 µg/m3, with means 38 µg/m3 for sprayers and 8.3 µg/m3 for hosemen. Hexamethylene diisocyanate means were 5.95 µg/m3 for sprayers and 0.645 µg/m3 for hosemen. Total reactive isocyanate group--the total of monomer and oligomer as NCO group mass--showed 6 of 15 personal samples exceeded the United Kingdom Health and Safety Executive workplace exposure limit of 20 µg/m3, with means 50.9 µg/m3 for sprayers and 7.29 µg/m3 for hosemen. Several exposure limits were exceeded, reinforcing continued use of personal protective equipment. The supply rate, 94.4 m3/s (200,000 cfm), produced a velocity of 8.58 m/s (157 fpm) at the supply filter, while the exhaust rate, 68.7 m3/s (146,000 cfm), drew 1.34 m/s (264 fpm) at the exhaust filter. Midway between supply and exhaust locations, the velocity was 0.528 m/s (104 fpm). Supply rate exceeding exhaust rate created re-circulations, turbulence, and fugitive emissions, while wasting energy. Smoke releases showing more effective ventilation here than in other aircraft painting facilities carries technical feasibility relevance.

Can volatile organic metabolites be used to simultaneously assess microbial and mite contamination level in cereal grains and coffee beans?

A novel approach based on headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-ToFMS) was developed for the simultaneous screening of microbial and mite contamination level in cereals and coffee beans. The proposed approach emerges as a powerful tool for the rapid assessment of the microbial contamination level (ca. 70 min versus ca. 72 to 120 h for bacteria and fungi, respectively, using conventional plate counts), and mite contamination (ca. 70 min versus ca. 24 h). A full-factorial design was performed for optimization of the SPME experimental parameters. The methodology was applied to three types of rice (rough, brown, and white rice), oat, wheat, and green and roasted coffee beans. Simultaneously, microbiological analysis of the samples (total aerobic microorganisms, moulds, and yeasts) was performed by conventional plate counts. A set of 54 volatile markers was selected among all the compounds detected by GC×GC-ToFMS. Principal Component Analysis (PCA) was applied in order to establish a relationship between potential volatile markers and the level of microbial contamination. Methylbenzene, 3-octanone, 2-nonanone, 2-methyl-3-pentanol, 1-octen-3-ol, and 2-hexanone were associated to samples with higher microbial contamination level, especially in rough rice. Moreover, oat exhibited a high GC peak area of 2-hydroxy-6-methylbenzaldehyde, a sexual and alarm pheromone for adult mites, which in the other matrices appeared as a trace component. The number of mites detected in oat grains was correlated to the GC peak area of the pheromone. The HS-SPME/GC×GC-ToFMS methodology can be regarded as the basis for the development of a rapid and versatile method that can be applied in industry to the simultaneous assessment the level of microbiological contamination and for detection of mites in cereals grains and coffee beans.

Airborne molds and bacteria, microbial volatile organic compounds (MVOC), plasticizers and formaldehyde in dwellings in three North European cities in relation to sick building syndrome (SBS).

There are few studies on associations between airborne microbial exposure, formaldehyde, plasticizers in dwellings and the symptoms compatible with the sick building syndrome (SBS). As a follow-up of the European Community Respiratory Health Survey (ECRHS II), indoor measurements were performed in homes in three North European cities. The aim was to examine whether volatile organic compounds of possible microbial origin (MVOCs), and airborne levels of bacteria, molds, formaldehyde, and two plasticizers in dwellings were associated with the prevalence of SBS, and to study associations between MVOCs and reports on dampness and mold. The study included homes from three centers included in ECRHS II. A total of 159 adults (57% females) participated (19% from Reykjavik, 40% from Uppsala, and 41% from Tartu). A random sample and additional homes with a history of dampness were included. Exposure measurements were performed in the 159 homes of the participants. MVOCs were analyzed by GCMS with selective ion monitoring (SIM). Symptoms were reported in a standardized questionnaire. Associations were analyzed by multiple logistic regression. In total 30.8% reported any SBS (20% mucosal, 10% general, and 8% dermal symptoms) and 41% of the homes had a history of dampness and molds There were positive associations between any SBS and levels of 2-pentanol (P=0.002), 2-hexanone (P=0.0002), 2-pentylfuran (P=0.009), 1-octen-3-ol (P=0.002), formaldehyde (P=0.05), and 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (Texanol) (P=0.05). 1-octen-3-ol (P=0.009) and 3-methylfuran (P=0.002) were associated with mucosal symptoms. In dwellings with dampness and molds, the levels of total bacteria (P=0.02), total mold (P=0.04), viable mold (P=0.02), 3-methylfuran (P=0.008) and ethyl-isobutyrate (P=0.02) were higher. In conclusion, some MVOCs like 1-octen-3-ol, formaldehyde and the plasticizer Texanol, may be a risk factor for sick building syndrome. Moreover, concentrations of airborne molds, bacteria and some other MVOCs were slightly higher in homes with reported dampness and mold.

[Indoor air guide values for methyl isobutyl ketone ]. / Richtwerte für Methylisobutylketon in der Innenraumluft.

The German Working Group on Indoor Guidelines of the Indoor Air Hygiene Committee and of the Supreme State Health Authorities is issuing indoor air guide values to protect public health. No reliable human studies are available for health evaluation of methyl isobutyl ketone (MIBK) in indoor air. In a well documented chronic inhalation animal study with rats assessed as reliable, nephrotoxic effects were observed, which led to an increased incidence and severity of the chronic progressive nephropathy, especially in females. Using a benchmark approach the Working Group assessed a BMDL10 of 57 mg MIBK/m³ for continuous exposure for the endpoint nephrotoxicity. By applying an interspecies factor of 2.5, a factor of 10 for interindividual variability, and a factor of 2 to account for the higher respiratory rate of children compared to adults, a health hazard guide value (RW II) of 1 mg MIBK/m³ indoor air is obtained. A precautionary guide value of 0.1 mg MIBK/m³ indoor air is recommended.

The vertical distributions of VOCs in the atmosphere of Beijing in autumn.

Volatile organic compounds (VOCs) in the air of Beijing City were measured at the heights of 8, 32, 140 and 280 m on the Beijing 325 m meteorological tower in autumn 2005. Concentrations of fifty-five compounds were determined by quantitative analytical methods. Our study utilized GC/MS analysis of 0.5 l air sample that were cryo-concentrated prior to analysis. The vertical distributions of VOCs were also investigated using 1-butene, isopentane, dichloromethane and toluene as representative compounds of several different categories. It is shown that 1-butene followed by 2-butene, isopentane followed by n-pentane, dichloromethane followed by chloroform and toluene followed by benzene are the most abundant compounds in the categories of alkene, alkane, halocarbon and aromatic hydrocarbon, respectively. The concentrations of TVOCs range from 51.2+/-39.7 ppb to 83.6+/-44.4 ppb on clear days, but from 62.9+/-19.0 ppb to 105.0+/-59.2 ppb on haze days. While alkenes and halocarbons contribute little to TVOCs, alkanes provide the largest percentage, ranging from about 46% to 63% at four different heights, which are followed by aromatic hydrocarbons ranging from about 15% to 27%. The vertical distributions of VOCs are complex. On clear days most distribution profiles show a decreasing trend with increasing height. On haze days, however, they exhibit first a decrease with increasing altitude from 8 m to 140 m and then a significant increase at 280 m. These results are understood by analyzing how the vertical distributions of VOCs are affected jointly by several factors such as meteorological parameters and transport property. In addition, principal components analysis (PCA) and cluster analysis show that VOCs have different origins at different heights.

Determination of gas phase adsorption isotherms--a simple constant volume method.

Single and ternary solute gas phase adsorption isotherms were conducted in this study to evaluate the effectiveness of a simple constant volume method, which was utilized by using Tedlar gas sampling bags as a constant volume batch reactor. For this purpose, gas phase adsorption of toluene, methyl ethyl ketone (MEK), and methyl isobutyl ketone (MIBK) on two types of activated carbons, BPL-bituminous base and OVC--coconut base, were investigated. For the single solute adsorption, the experimental adsorption data were found to be well correlated with Freundlich and Myers adsorption equations. The pore size distribution of adsorbents was found to affect their adsorption capacities; its effect was dependant on the solute concentration. The ternary adsorption experimental isotherms were accurately predicted by using the well-known model, i.e., ideal adsorbed solution theory (IAST).

Distribution of aged 14C-PCB and 14C-PAH residues in particle-size and humic fractions of an agricultural soil.

Organic matter is considered to be the single most importantfactor limiting availability and mobility of persistent organic pollutants (POPs) in soil. This study aimed to characterize the distribution of 14C-PCB (congeners 28 and 52) and 14C-PAH (fluoranthene and benzo[a]pyrene) residues in an Orthic Luvisol soil obtained from two lysimeter studies initiated in 1990 at the Agrosphere Institute (Forschungszentrum Jülich GmbH, Germany). The lysimeter soils contained a low-density OM fraction, isolated during soil washing, which contained a significant fraction (3-12%) of the total 14C-activity. Soils were also fractionated according to three particle sizes: >20, 20-2, and <2 microm. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20-2 microm > (<2 microm) approximately (>20 microm) for the PCBs. Relative affinity values of 14C-activity for the different particle sizes varied in the order 20-2 microm > (<2 microm) > (>20 microm) for the PAHs. The distribution of 14C-PCB or 14C-PAH residues in the organic and inorganic matrixes of the particle-size fractions was determined using methyl isobutyl ketone (MIBK). 14C-PCB and 14C-PAH-associated activities were primarily located in the humin fraction of the 20-2 and <2 microm particle-size fractions of the soil. A small fraction was associated with the fulvic and humic acid fractions; these were quantitatively more important for the PAHs than the PCBs. There appeared to be a high degree of association of 14C-activity with the mineral fraction following MIBK separation of the humic fractions, ranging between 8 and 52% for 14C-PCBs and 57-80% for 14C-PAHs. The mineral (inorganic) component of the soils apparently played a significant (previously unreported) role in the sequestration of both PCBs 28 and 52 and the PAHs fluoranthene and benzo[a]pyrene.

High-speed gas chromatographic analysis of solvents in pharmaceuticals using solid phase microextraction.

A simple, inexpensive and rapid analytical approach for the determination of organic volatile impurities in pharmaceutical drug substances is developed, where sample preparation step was conducted using solid phase microextraction (SPME), followed by a fast GC separation. With an extraction time between 3 and 5 min and separation of 13 solvents in less than 3 min employing fast temperature programming using resistively heated column, organic volatile impurities can be analyzed within a total analysis time of 6-9 min. Various SPME phases were evaluated towards sensitivity and selectivity for the extraction of 13 commonly found solvents in drug substances dissolved in dimethyl sulfoxide and water. A 2-cm Carboxen/polydimethyl siloxane/divinylbenzene (Carboxen/PDMS/DVB) phase and a 65-microm DVB/PDMS phase showed better sensitivity towards these solvents when extracted from organic and aqueous matrix in comparison with the sensitivity obtained with direct injection approach. Extraction parameters such as extraction time, extraction stir rate, etc. are discussed. %RSD of peak area of replicate extraction was between 2 and 10% when 100 microm PDMS was used for extracting solvents from aqueous matrix. When DVB/PDMS fiber was evaluated for precision, %RSD of peak area from replicate extractions of solvents from organic matrix was between 2 and 8%. One-hundred micrometer PDMS showed excellent linearity from 10 to 500 microg/ml for analytes extracted from water solutions. On the other hand, DVB/PDMS phase showed better linearity than Carboxen/PDMS/DVB fiber when it was used to extract analytes in the concentration range of 10-5000 microg/ml from organic matrix.

Analysis of residual solvents in ampicillin powder by headspace spectrophotometric method.

In this study a headspace spectrophotometric method is proposed for analysis of dichloromethane and isobutyl methyl keton (IBMK) residues in the ampicillin powder. Ampicillin is dissolved in 1 M NaOH in the vessel of an arsenic analyzer unit of an atomic absorption spectrophotometer. After 3-min stirring, the headspace has flowed by air into the flow-through cell and its absorbance is read at 196 nm, as emitted by a selenium hollow cathode lamp. The absorbance of the headspace is read in two cases (in the presence and absence of MnO4- ion). In the former case, the absorbance is only related to dichloromethane; in the latter, it is related to both solvents. By this method both solvents are determined in the ampicillin samples. The obtained results are compared with gas chromatography (GC) data. These results have good agreement. The proposed method is very rapid, selective and repeatable. Other solvents present, such as isopropyl alcohol, ethylacetate and triethylamine, are not interfering.

Evaluation of individual components of plum odor as potential attractants for adult plum curculios.

We evaluated olfactory attraction of overwintered plum curculio (PC) adults, Conotrachelus nenuphar, to 16 individual volatile components of unripe plum odor in the laboratory using a still-air dual-choice bioassay system and in the field using baited cotton dental wicks attached to boll-weevil traps placed on the ground beneath the canopy of unsprayed apple trees. Two compounds, ethyl isovalerate and limonene, were significantly attractive in both laboratory bioassays and field experiments. In laboratory bioassays, as concentration was decreased across five orders of magnitude, a greater number of compounds elicited responses suggestive of attractancy (except at the lowest concentration). Even so, linalool, 2-hexanone, and 3-hydroxy-2-butanone were the only other compounds showing significant attractiveness in laboratory bioassays, but none of these (nor any other compounds) were significantly attractive in field assays. We suggest that the use of ethyl isovalerate and/or limonene as odor attractants offers potential to increase the efficacy of current traps for monitoring PCs immigrating into fruit orchards during spring.

A predictive model for vapor concentration in a nose-only inhalation chamber.

A unique nose-only inhalation chamber was designed and constructed to deliver uniform concentrations of gas, vapor, and aerosol contaminants to mice. This research investigated the fluid dynamics of a vaporous contaminant in the vertical flow chamber. The vapor was introduced by allowing the liquid phase of the contaminant to evaporate freely into the chamber interior. A contaminant mass transfer model was developed to predict concentrations generated by the system. The mathematical model of the system used clean airflow, liquid surface area, thickness of the stagnant air layer covering the liquid, system pressure, contaminant diffusion coefficient, and contaminant vapor pressure to compute the vapor concentration delivered to exposure ports. The equation was verified by placing various containers of methyl isobutyl ketone in the chamber and determining with a photospectrometer the resulting equilibrium concentrations. Vapor pressure, diffusion coefficient, and system pressure were held constant while airflow, surface area, and stagnant air layer thickness were varied systematically within the chamber. The resulting empirical data points were compared to the curves predicted by the theoretical model. Empirical concentrations fell within 0 to 48% of the theoretical values, showing that the equation can be used to choose values for airflow, surface area, and stagnant air layer thickness that will result in chamber concentrations in close proximity to the target concentration. If an exact concentration is essential, parameters may be individually adjusted to converge on the target concentration.

Screening method for determination of high levels of cadmium, lead, and copper in foods by polarized Zeeman atomic absorption spectrometry using discrete nebulization technique.

A screening method for determination of cadmium, lead, and copper in foods was developed. The sample (1-3 g) is digested with HNO3-H2SO4-HClO4 in a centrifuge tube attached to a straight glass tube that prevents loss of HNO3 by volatilization. After digestion, potassium iodide, H2SO4, and MIBK (4-methyl 2-pentanone) are added, and the metals are extracted with MIBK as metal iodides. The MIBK solution is injected and the metals are determined by flame polarized Zeeman atomic absorption spectrometry using a discrete nebulization technique. Recoveries of metals from fortified milk powder, unpolished rice, fish, beef, peanut butter, apple, and cabbage were satisfactory. The analytical results for NBS Oyster Tissue and NIES Pepperbush, Chlorella, and Mussel agreed with certified or reference values except lead in Pepperbush. The limits of quantitation for cadmium, lead, and copper were 0.01, 0.09, and 0.02 ppm, respectively. This method is simple and safe for routine analysis of high levels of cadmium, lead, and copper in foods.

Analysis of n-hexane, 2-hexanone, 2,5-hexanedione, and related chemicals by capillary gas chromatography and high-performance liquid chromatography.

Analytical methods, using capillary gas chromatography and normal-phase high-performance liquid chromatography, were developed for the analysis of the neurotoxic chemicals n-hexane, 2-hexanone, and 2,5-hexanedione and their suspected metabolites. Two gas chromatographic methods, using a 50-m glass capillary OV 101 column and cyclohexane as an internal standard, were employed. In both methods, the injector and detector temperatures were 220 and 280 degrees C, respectively. In method I the following temperature program was used: isothermic at 50 degrees C for 30 min, followed by a temperature increase of 10 degrees C/min to a final temperature of 180 degrees C, which was then maintained for 7 min. This method was used to analyze the following compounds: n-hexane, 2,5-dimethylfuran, 2-hexanone, 3-hexanone, hexanal, 1-hexanol, 2-hexanol, 3-hexanol, 5-hydroxy-2-hexanone, gamma-valerolactone, 2,5-hexanedione, and 2,5-hexanediol. Method II, which was developed for n-hexane and eight of its more common metabolites, used the following temperature program: isothermic at 70 degrees C for 15 min, followed by a temperature increase of 40 degrees C/min to a final temperature of 220 degrees C, which was maintained for 5 min. A linear relationship between peak area and amount injected was observed over a 100-fold range. The minimum detectable amounts ranged from 0.05 to 1 microgram, depending on the compound. Normal-phase HPLC, using a 5-micron silica cartridge fitted into an RCM-100 radial-compression separation system, was utilized to analyze 2-hexanone and its metabolites 2,5-dimethylfuran, gamma-valerolactone, 5-hydroxy-2-hexanone, and 2,5-hexanedione.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection and quantitation of multiple volatile compounds in tissues by GC and GC/MS.

Qualitative and quantitative analysis of tissues and body fluids for multiple volatile organic compounds were performed by a combination of packed and open tubular capillary GC and GC/MS. This paper describes methods for such analyses in a case involving the exposure of two persons to methyl ethyl ketone, methyl isobutyl ketone, toluene and the three isomeric xylenes. Tissue and body fluid concentrations of these substances in the two decedents are presented and discussed briefly.

Simultaneous determination of n-hexane, 2-hexanone and 2,5-hexanedione in biological tissues by gas chromatography mass spectrometry.

A quantitative method is reported for the determination of n-hexane, 2-hexanone and 2,5-hexanedione in biological tissues by stable isotope dilution using gas chromatography mass spectrometry. n-[2H14]Hexane, 2-[2H5]hexanone and 2,5-[2H10]hexanedione are used as the isotopic diluents. After tissue homogenization and extraction of the three compounds in the presence of the deuterated internal standards, analysis is carried out in a single gas chromatographic injection by selected ion monitoring. Principal advantages of the technique are the ease of sample handling, rapidity of analysis and low limits of detection. The methodology is used to determine the organ distribution, pharmacokinetics and metabolism of n-hexane to 2-hexanone and 2,5-hexanedione in rats following inhalation exposure.