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PubMed1988

Studies on some iridium(III) complexes with Schiff bases derived from amino carboxylic acids.

The reactions of iridium(III) chloride with different Schiff bases gave complexes of types [Ir(SB)3], [Ir(SB')Cl(H2O)2], [Ir(SB'')Cl2]n, [Ir(SB'' ')Cl(H2O)]n (SBH = Schiff bases derived from anthranilic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde or m-hydroxyacetophenone; SB'H2 = Schiff bases derived from anthranilic acid and salicylaldehyde or o-hydroxyacetophenone; SB''H = Schiff bases derived from p-aminobenzoic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde, or m-hydroxyacetophenone; SB'' 'H2 = Schiff bases derived from p-aminobenzoic acid and salicylaldehyde or o-hydroxyacetophenone). These complexes have been characterized on the basis of elemental analyses, conductance, magnetic moment, and spectral (electronic, i.r., and 1H n.m.r.) data. The electronic spectra reveals octahedral geometry for these complexes except for [Ir(SB'')Cl2]n, which is trigonal bipyramidal. The thermal behavior of these complexes has also been studied by TG, DTG, and DSC techniques. The different kinetic parameters, viz., order of reaction, activation of energy, and heat of reaction were calculated. The antifungal and antiviral activities of the complexes with Schiff bases derived from anthranilic acid have also been investigated.

4-Aminobenzoic Acid↗
PubMed1987

Analysis of nandrolone esters in oily injections by reversed-phase high-performance liquid chromatography.

A specific liquid chromatographic (HPLC) procedure is presented for the analysis of nandrolone esters (phenylpropionate, decanoate and undecanoate) in commercial oily injections. The analysis was carried out under isocratic, reversed-phase (RP8 column) conditions using a UV detector (240 nm). The system discriminates between nandrolone alcohol, a potential impurity, and its esters and permits the quantitation of trace benzaldehyde derived from the oxidative degradation of benzyl alcohol. The proposed HPLC method was found to be more specific and accurate than the pharmacopoeial spectrophotometric assay procedure (isoniazid reagent). The interference of benzaldehyde with the isoniazid method was also investigated.

Journal Article↗
PubMedDate not supplied

A histochemical study of the distribution of aldehyde dehydrogenase activity in brain structures of rats with genetically different alcohol-related behaviour.

Brain samples from rats genetically selected for high or low voluntary alcohol intake (AA and ANA strains) or for differences in alcohol-induced motor incoordination (AT and ANT strains) were analyzed by histochemistry for aldehyde dehydrogenase (EC 1.2.1.3; ALDH) activity in various CNS structures. All strains exhibited the highest ALDH activities in neurons of the mesencephalic tract of trigeminal nerve nucleus and in spinal cord motoneurons, while the lowest activities were observed in the somatosensory cortex. Although the general distribution pattern of ALDH activity was similar in the genetically selected strains, some potentially important differences were observed. AA rats with high voluntary alcohol consumption had lower ALDH activity (with acetaldehyde as substrate) in the neuropil of the olfactory tubercle but higher activity (with benzaldehyde as substrate) in the spinal cord motoneurons, Purkinje cells and capillary endothelium of the cerebellum as compared to the corresponding structures from the alcohol avoiding ANA rats. Alcohol-resistant AT rats had higher ALDH activity, with benzaldehyde, in most CNS structures than did the alcohol-sensitive ANT's, significantly so in the lamina II of the somatosensory cortex and the neurons of the lateral hypothalamic area. This relationship was also found with acetaldehyde as substrate in the neurons of the hypothalamic arcuate nuclei and in cerebellar capillaries, but the ANT's had the higher activity in the neurons of the cerebral cortex V lamina. We suggest that some of the differences observed may relate to the differences between the rat strains with respect to voluntary alcohol intake and alcohol-induced motor incoordination.

Alcohol Drinking↗
PubMed2005

Volatile carbonylic compounds in downtown Santiago, Chile.

Formaldehyde, acetaldehyde, acetone, propanal, butanal, 2-butenal, 3-methylbutanal, hexanal, benzaldehyde, 2-methylbenzaldehyde, and 2,5-dimethylbenzaldehyde were measured during six spring days at downtown Santiago de Chile. Measurements were performed 24h/day and averaged over three hour periods. The averages of the maxima (ppbv) were, formaldehyde: 3.9+/-1.4; butanal: 3.3+/-3.4; acetaldehyde: 3.0+/-0.9; acetone: 2.4+/-1.0; 2-butenal: 0.56+/-0.52; propanal: 0.46+/-0.21; benzaldehyde: 0.34+/-0.3; 3-butanal: 0.11+/-0.05; hexanal: 0.11+/-0.08; 2-methylbenzaldehyde: 0.08+/-0.05; 2,5-dimethylbenzaldehyde: 0.05+/-0.03. Aliphatic aldehydes (C1-C3) are strongly correlated among them and weakly with primary (toluene) and secondary (ozone plus nitrogen dioxide or PAN) pollutants. In particular, the correlation between acetaldehyde and propanal values remains even if diurnal and nocturnal data are considered separately, indicating similar sources. All these aldehydes present maxima values in the morning (9-12h) and minima at night (0-3h). The best correlation is observed when butanal and 2-butenal data are considered (r=0.99, butanal/2-butenal=6.2). These compounds present maxima values during the 3-6h period, with minima values in the 0-3h period. These data imply a strong pre-dawn emission. Other aldehydes show different daily profiles, suggesting unrelated origins. Formaldehyde is the aldehyde whose concentration values best correlate with the levels of oxidants. The contribution of primary emissions and photochemical processes to formaldehyde concentrations were estimated by using a multiple regression. This treatment indicates that (32+/-16)% of measured values arise from direct emissions, while (79+/-23)% is attributable to secondary formation.

Acetone↗
PubMed2004

Highly sensitive and selective determination of 9, 10-phenanthrenequinone in airborne particulates using high-performance liquid chromatography with pre-column derivatization and fluorescence detection.

9,10-Phenanthrenequinone (PQ), is one of the components of diesel exhaust particulates, has potent harmful effects on human health. For the determination of PQ in airborne particulates, a highly sensitive and selective high-performance liquid chromatography (HPLC) method was developed with fluorescence detection following the pre-column fluorescent derivatization. PQ was derivatized with benzaldehyde as a derivatizing reagent in the presence of ammonium acetate to give fluorescent 2-phenyl-1H-phenanthro [9,10-d] imidazole. The maximum fluorescence intensity of the derivative was observed by the reaction with 0.2M benzaldehyde and 0.5 M ammonium acetate at 100 degrees C for 30 min. The HPLC separation of fluorescent derivative of PQ was performed within 20 min on an ODS column with a mixture of acetonitrile-water (55:45, v/v) as a mobile phase. Highly sensitive and selective determination of PQ was attained with the detection limit of 5 fmol (S/N = 3). By the proposed method, PQ in airborne particulates was successfully determined in the range 0.26-0.30 ng/m3 (n = 3).

Air Pollutants↗
PubMed2000

Electrophysiological studies of olfaction in the whip spider Phrynus parvulus (Arachnida, Amblypygi).

The olfactory response of the whip spider Phrynus parvulus from Costa Rica was examined using a technique analogous to that used for insect electroantennograms on the tarsi of the antenniform legs which bear multiporous sensilla. Responses to 42 chemicals representing different chain lengths of alkanes, carboxylic acids, alcohols, aldehydes, and ketones, as well as some esters, monoterpenes, and phenolics were examined. Fifty-four percent of the chemicals tested elicited responses. Concentration-response curves were generated for guaiacol, hexanal, methyl salicylate, benzaldehyde, octanoic acid, and linalool. Guaiacol, benzaldehyde, and hexanol elicited the greatest responses and no differences were detected between the sexes. Compounds with chain lengths of six carbon atoms generated strong responses and most monocarboxylic acids and ring compounds elicited responses. Some compounds produced increases in potential believed to arise from a hyperpolarizing effect on the neurons. The broad spectrum of chemicals to which these animals respond is similar to results of other studies examining the general olfactory sense of insects. It is possible that odor learning plays a significant role in the behavior of amblypygids.

Journal Article↗
PubMed2003

Increased EAG responses of tortricid moths after prolonged exposure to plant volatiles: evidence for octopamine-mediated sensitization.

As measured by electroantennograms (EAG), both male and female obliquebanded leafrollers, Choristoneura rosaceana (Harris), and redbanded leafrollers, Argyrotaeniavelutinana (Walker), were similarly sensitive to host-related plant volatiles: trans-2-hexenal, benzaldehyde, 1-hexenol, cis-3-hexen-1-ol, geraniol, linalool, (+)-limonene, hexenal and trans-2-hexenol. Females of both species were similarly sensitive to the shared major component of their sex-attractant pheromone ((Z)11-14:Ac). Continuous 60 min pre-exposure of male and female C. rosaceana and A. velutinana to successively higher concentrations of a mixture of the nine plant volatiles in Teflon chambers with continuous air exchange caused a dosage-dependent increase in subsequent responsiveness (sensitization) to green leaf volatiles, as measured by EAGs. In addition, 60 min of pre-exposure of male C. rosaceana to certain individual volatiles ((+)-limonene, geraniol, benzaldehyde) increased EAGs nearly as much as did the mixture of nine volatiles. Pre-exposures to the nine plant-volatile mixture at concentrations achieved by 100 microg and 1 mg loading dosages in 100 microl of mineral oil significantly increased EAG depolarization to pheromone (cross-sensitization) in males but not females of both moth species. Antennae of male C. rosaceana pre-injected with 100 microg of octopamine (OA) without volatile pre-exposure exhibited sensitization nearly identical to that induced by pre-exposing moths to sensitizing concentrations of the plant-volatile mixture. Moreover, injection of the OA antagonist chlorpromazine (CP) blocked sensitization by the plant-volatile pre-exposure. Collectively, these findings suggest that exposures of tortricid moths to certain host-plant related volatiles may modulate subsequent olfactory sensitivity to behaviorally relevant chemical cues and that plant-volatile induced sensitization may be octopamine mediated.

Adrenergic alpha-Agonists↗
PubMed2002

Non-specific olfactory aversion induced by intrabulbar infusion of the GABA(A) receptor antagonist bicuculline in young rats.

On postnatal day 12, young rats show an aversion to an odor to which they had been exposed along with presentations of foot shock on postnatal day 11. The acquisition of this aversive learning involves and requires disinhibition of the mitral/tufted cells induced by centrifugal noradrenergic activation during somatosensory stimulation. This olfactory learning is established only for the odor to which the rat has been exposed during conditioning. Infusion of the GABA(A) receptor antagonist bicuculline at a high dose (2.0 nmol/each olfactory bulb) into the olfactory bulb in the presence of an odor is capable of developing olfactory aversive responses without somatosensory stimulation in young rats. The purpose of this study is to characterize the properties of bicuculline-induced aversive responses. In contrast to the odor specificity of aversive learning produced by odor-shock conditioning, bicuculline-induced aversive responses lack odor specificity. Namely, bicuculline infusion in the presence of a citral odor results, in a dose-dependent manner, in subsequent aversive responses to strange odors (benzaldehyde and vanillin) that have never been presented. Moreover, bicuculline infusion alone is sufficient to produce dose-dependent aversive responses to strange odors (citral, benzaldehyde and geraniol). From these results we suggest that disinhibition of mitral/tufted cells from granule cells by bicuculline infusion makes young rats aversive to strange odors non-specifically, as if the rats had learned the odor aversion as a result of odor exposure paired with foot shock. Different mechanisms of disinhibition of the mitral/tufted cells may underlie both the pharmacological manipulation and noradrenergic activation by somatosensory stimulation.

Animals↗
PubMed2004

Synthesis, spectroscopic characterization, redox properties and catalytic activity of some ruthenium(II) complexes containing aromatic aldehyde and triphenylphosphine or triphenylarsine.

A series of new mixed ligand penta-coordinated square pyramidal ruthenium(II) complexes containing benzaldehyde or its substituents and triphenylphosphine or triphenylarsine have been synthesized and characterized. In the electronic spectra, three well-defined peaks in the visible region were observed and assigned to d-d transitions in D(4h) and low spin axially distortion from O(h) symmetry. The spectrochemical parameters of the complexes were calculated and placed the ligands in the middle of the spectrochemical series. The redox properties and stability of the complexes toward oxidation were related to the electron-withdrawing or releasing ability of the substituent in the phenyl ring of the benzaldehyde. The electron-withdrawing substituents stabilized Ru(2+) complexes, while electron-donating groups favored oxidation to Ru(3+). The mechanism and kinetics of the catalytic oxidation of benzyl alcohol by the complex [RuCl(2)(Pph(3))(C(6)H(5)CHO)(2)] in the presence of N-methylmorpholine-N-oxide have also been studied.

Aldehydes↗
PubMed2002

Feasibility of collection and analysis of airborne carbonyls by on-sorbent derivatization and thermal desorption.

The most commonly used method for analysis of airborne carbonyls is to collect the analytes on solid sorbents coated with a suitable derivatization agent, followed by solvent desorption and liquid injection for analysis by high-pressure liquid chromatography. We have explored a new approach by combining on-sorbent derivatization and thermal desorption to measure airborne carbonyls. More specifically, carbonyls in the air are collected onto an O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA)-coated Tenax sorbent packed in a tube with dimensions identical to those of a gas chromatography (GC) injector liner. The derivatives are then released by in-injection port thermal desorption to a GC column for analysis. Gaseous carbonyls, including formaldehyde, acetaldehyde, benzaldehyde, glyoxal, and methylglyoxal, at ppbv levels are shown to be effectively collected (> or = 92% collection efficiency) onto the sampling tubes at a flow rate of 20 mL/min under both < 1% and 71% relative humidity. The collection efficiency drops as the sampling flow rate increases, and the degree of decrease is compound dependent. The derivatization agent, at a level of approximately 127 nmol/tube, is thermally desorbed and eluted from the GC column without compromising the determination of any carbonyl-PFBHA derivatives. Detection limits of low ppbv to sub-ppbv are achieved for a sample air volume of 4.8 L. Using this new method, we have measured formaldehyde, acetaldehyde, benzaldehyde, glyoxal, and methylglyoxal to be 4.9-16.3, 0.6-8.2, <5.9, 0.5-4.1, and <2.4 ppbv, respectively, in the ambient atmosphere at the university bus stop. This method is less labor intensive than the solvent desorption technique and avoids use of organic solvents. Other classes of airborne polar species can be measured through the same approach by selecting an appropriate derivatization agent.

Journal Article↗
PubMed2005

On-line derivatization for resonance-enhanced multiphoton ionization time-of-flight mass spectrometry: detection of aliphatic aldehydes and amines via reactive coupling of aromatic photo ionization labels.

Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry (REMPI-TOFMS) is a powerful technique for the on-line analysis of aromatic compounds with unique features regarding selectivity and sensitivity. Aliphatic compounds, however, are difficult to address by REMPI due to their unfavorable photo ionization properties. This paper describes the proof of concept for an on-line derivatization approach for converting nonaromatic target analytes into specific, photoionizable aromatic derivatives that are readily detectable by REMPI-TOFMS. A multichannel silicone trap or poly(dimethylsiloxane) (PDMS) open tubular capillary was used as a reaction medium for the derivatization of volatile alkyl aldehydes and alkylamines with aromatic "photoionization labels"and to concentrate the resulting aromatic derivatives. The aldehydes formaldehyde, acetaldehyde, acrolein, and crotonal, which when underivatized are poorly detectable by REMPI, were converted into their easily photoionizable phenylhydrazone derivatives by the on-line reaction with phenylhydrazine as reagent. Similarly, the methyl-, ethyl-, propyl-, and butylamines were converted into their REMPI-ionizable benzaldehyde alkylimine derivatives by the on-line reaction with benzaldehyde as reagent. The derivatives were thermally desorbed from the PDMS matrix and transferred into the REMPI-TOFMS for detection. The REMPI-TOFMS detection limits obtained for acetaldehyde; acrolein; crotonal; and methyl-, ethyl-, propyl-, and butylamine using this photo ionization labeling method were in the sub-parts-per-million range and, thus, readily below the permissible exposure limits set by OSHA.

Aldehydes↗
PubMed2004

Spongiform immobilization architecture of ionotropy polymer hydrogel coentrapping alcohol oxidase and horseradish peroxidase with octadecylsilica for optical biosensing alcohol in organic solvent.

An organic-phase optical alcohol biosensor consisting of alcohol oxidase and horseradish peroxidase coimmobilized in a spongiform hydrogel matrix of hydroxethyl carboxymethyl cellulose, an adduct of 3-methoxy-4-ethoxy benzaldehyde, 4-tert-butylpyridinium acetohydrazone, silica gel particles, and octadecylsilica particles in conjunction with an optical oxygen transducer has been successfully fabricated. The novel enzyme entrapment structure was mainly characterized with desirable solvent permeability, high efficiency of mass transfer for reactants, and good accessibility and stability of the immobilized enzymes. The biosensor could work in water-miscible solvent such as a solvent mixture of acetonitrile and phosphate aqueous buffer, as well as hydrophobic organic solvent such as n-hexane. The biosensor had the highest sensitivity to methanol in both solvent systems. Under the stop-flow mode, the biosensor had the analytical working ranges from 80 microM to 90 mM methanol in n-hexane and 0.10 to 90 mM methanol in acetonitrile/buffer. When the biosensor functioned in n-hexane, it could take benzaldehyde as an alcohol substrate and was free from any pH disturbance. In the presence of coimmobilized horseradish peroxidase, the operational life of the biosensor was 60 assays and the shelf life was longer than two weeks. The biosensor has been satisfactorily applied to the determination of methanol in commercial gasoline-methanol blend samples.

Alcohol Oxidoreductases↗
PubMed1993

Molecular cloning of testicular 20 alpha-hydroxysteroid dehydrogenase: identity with aldose reductase.

Complementary DNA (cDNA) clones encoding bovine testicular 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) have been isolated from a bovine testicular lambda gt11 library using polyclonal antibodies against 20 alpha-HSD and DNA probe hybridization. Nucleotide sequencing of three independently isolated clones was used to establish a composite cDNA sequence that encodes the enzyme. It contains a coding sequence of 921 nucleotides, a stop codon, and a 264-nucleotide 3'-noncoding segment which allowed deduction of the amino acid sequence of the enzyme. A computer homology search of the 20 alpha-HSD cDNA performed against the GenBank DNA sequence database revealed it to be identical with bovine lens aldose reductase (alditol:NADPH oxidoreductase; EC 1.1.1.21), and a literature search reveals the deduced amino acid sequence to be identical with that reported for the bovine enzyme. Sequences obtained from the N-terminus of purified testicular 20 alpha-HSD and from random peptides obtained by treatment with endopeptidase Lys-C are all identical with regions of the deduced amino acid sequence of 20 alpha-HSD and/or the published sequence of aldose reductase. Further, the enzyme purified to homogeneity by following activity with 17-hydroxyprogesterone as a substrate was shown to reduce glucose, glyceraldehyde, and benzaldehyde (all classic aldose reductase substrates). Finally, 17-hydroxyprogesterone inhibited the reduction of benzaldehyde and glyceraldehyde. Because aldose reductase has been implicated in the etiology of diabetic complications, acceptance of steroid substrates may offer new implications for therapy.

20-Hydroxysteroid Dehydrogenases↗
PubMed1990

Mandelate pathway of Pseudomonas putida: sequence relationships involving mandelate racemase, (S)-mandelate dehydrogenase, and benzoylformate decarboxylase and expression of benzoylformate decarboxylase in Escherichia coli.

The genes that encode the five known enzymes of the mandelate pathway of Pseudomonas putida (ATCC 12633), mandelate racemase (mdlA), (S)-mandelate dehydrogenase (mdlB), benzoylformate decarboxylase (mdlC), NAD(+)-dependent benzaldehyde dehydrogenase (mdlD), and NADP(+)-dependent benzaldehyde dehydrogenase (mdlE), have been cloned. The genes for (S)-mandelate dehydrogenase and benzoylformate decarboxylase have been sequenced; these genes and that for mandelate racemase [Ransom, S. C., Gerlt, J. A., Powers, V. M., & Kenyon, G. L. (1988) Biochemistry 27, 540] are organized in an operon (mdlCBA). Mandelate racemase has regions of sequence similarity to muconate lactonizing enzymes I and II from P. putida. (S)-Mandelate dehydrogenase is predicted to be 393 amino acids in length and to have a molecular weight of 43,352; it has regions of sequence similarity to glycolate oxidase from spinach and ferricytochrome b2 lactate dehydrogenase from yeast. Benzoylformate decarboxylase is predicted to be 499 amino acids in length and to have a molecular weight of 53,621; it has regions of sequence similarity to enzymes that decarboxylate pyruvate with thiamin pyrophosphate as cofactor. These observations support the hypothesis that the mandelate pathway evolved by recruitment of enzymes from preexisting metabolic pathways. The gene for benzoylformate decarboxylase has been expressed in Escherichia coli with the trc promoter, and homogeneous enzyme has been isolated from induced cells.

Acetolactate Synthase↗
PubMed2004

Reaction of Pseudomonas fluorescens kynureninase with beta-benzoyl-L-alanine: detection of a new reaction intermediate and a change in rate-determining step.

Beta-benzoyl-DL-alanine was synthesized from alpha-bromoacetophenone and diethyl acetamidomalonate. The racemic amino acid was resolved by carboxypeptidase A-catalyzed hydrolysis of the N-trifluoroacetyl derivative. Beta-benzoyl-L-alanine is a good substrate of kynureninase from Pseudomonas fluorescens, with k(cat) and k(cat)/K(m) values of 0.7 s(-1) and 8.0 x 10(4) M(-1) s(-1), respectively, compared to k(cat) = 16.0 s(-1) and k(cat)/K(m) = 6.0 x 10(5) M(-1) s(-1) for L-kynurenine. In contrast to the reaction of L-kynurenine, beta-benzoyl-L-alanine does not exhibit a significant solvent isotope effect on k(cat) ((H)k/(D)k = 0.96 +/- 0.06). The pre-steady-state kinetics of the reaction of beta-benzoyl-L-alanine were investigated by rapid scanning stopped-flow spectrophotometry. The spectra show the formation of a quinonoid intermediate, with lambda(max) = 490 nm, in the dead time of the instrument, which then decays, with k = 210 s(-1), to form a transient intermediate with lambda(max) at 348 nm. In the presence of benzaldehyde, the 348 nm intermediate decays, with k = 0.7 s(-1), to form a quasistable quinonoid species with lambda(max) = 492 nm. Previous studies demonstrated that benzaldehyde can trap an enamine intermediate formed after the C(beta)-C(gamma) bond cleavage [Phillips, R. S., Sundararaju, B., and Koushik, S. V. (1998) Biochemistry 37, 8783-8789]. Thus, the 348 nm intermediate is kinetically competent. The position of the absorption maximum and shape of the band is consistent with a PMP-ketimine intermediate. The results from chemical quenching analysis do not show a burst of benzoate and, thus, also support the formation of benzoate as the rate-determining step. These data suggest that, in contrast to L-kynurenine, for which the rate-determining step was shown to be deprotonation of the pyruvate-ketimine intermediate [Koushik, S. V., Moore, J. A., III, Sundararaju, B., and Phillips, R. S. (1998) Biochemistry 37, 1376-1382], the rate-determining step in the reaction of beta-benzoyl-L-alanine with kynureninase is C(beta)-C(gamma) bond cleavage.

Alanine↗
PubMed2001

On-road emissions of carbonyls from light-duty and heavy-duty vehicles.

Vehicle emissions are a major source of carbonyls, which play an important role in atmospheric chemistry and urban air quality. Yet, little data are available for speciated carbonyls emitted by vehicles and especially by heavy-duty diesel vehicles. On-road vehicle emissions of carbonyls have been measured in May 1999 at the Tuscarora Mountain Tunnel, PA. Ten saturated aliphatic aldehydes, 4 saturated aliphatic ketones, 4 unsaturated aliphatic carbonyls, 4 aliphatic dicarbonyls, and 9 aromatic carbonyls have been identified and their concentrations measured. For light-duty (LD) vehicles, total carbonyl emissions were ca. 6.4 mg/km, and the 10 largest emission factors were, in decreasing order, those of formaldehyde (2.58 +/- 1.05 mg/km, ca. 40% of total carbonyls), acetone, acetaldehyde, heptanal, crotonaldehyde, 2-butanone, propanal, acrolein, methacrolein, and benzaldehyde. For weight class 7-8 heavy-duty diesel vehicles (7-8 HD), total carbonyl emissions were ca. 26.1 mg/km, and the 10 largest emission factors were, in decreasing order, those of formaldehyde (6.73 +/- 2.05 mg/km, ca. 26% of total carbonyls), acetaldehyde, acetone, crotonaldehyde, m-tolualdehyde, 2-pentanone, benzaldehyde, a C5 saturated aliphatic aldehyde isomer, 2,5-dimethylbenzaldehyde, and 2-butanone. Aromatic carbonyls, unsaturated aliphatic aldehydes, and aliphatic dicarbonyls represented larger fractions of the total carbonyl emissions for 7-8 HD vehicles than for LD vehicles. For HD vehicles, formaldehyde and acetaldehyde emission factors measured in this study are ca. 4-5 times lower than those measured in previous work. For LD vehicles, emission factors measured in this study are generally lower than those measured in earlier work and are about the same, within reported uncertainties, as those measured in 1992 in the same highway tunnel.

Automobiles↗
PubMed2001

On-road measurement of carbonyls in California light-duty vehicle emissions.

Emissions of carbonyls by motor vehicles are of concern because these species can be hazardous to human health and highly reactive in the atmosphere. The objective of this research was to measure carbonyl emission factors for California light-duty motor vehicles. Measurements were made at the entrance and exit of a San Francisco Bay area highway tunnel, in the center bore where heavy-duty trucks are not allowed. During summer 1999, approximately 100 carbonyls were identified, including saturated aliphatic aldehydes and ketones, unsaturated aliphatic carbonyls, aliphatic dicarbonyls, and aromatic carbonyls. Concentrations were measured for 32 carbonyls and were combined with NMOC, CO, and CO2 concentrations to calculate by carbon balance emission factors per unit of fuel burned. The measured carbonyl mass emitted from light-duty vehicles was 68 +/- 4 mg L(-1). Formaldehyde accounted for 45% of the measured mass emissions, acetaldehyde 12%, tolualdehydes 10%, benzaldehyde 7.2%, and acetone 5.9%. The ozone forming potential of the carbonyl emissions was dominated by formaldehyde (70%) and acetaldehyde (14%). Between 1994 and 1999, emission factors measured at the same tunnel for formaldehyde, acetaldehyde, and benzaldehyde decreased by 45-70%. Carbonyls constituted 3.9% of total NMOC mass emissions and 5.2% of NMOC reactivity. A comparison of carbonyl emissions with gasoline composition supports previous findings that aromatic aldehyde emissions are related to aromatics in gasoline. Carbonyl concentrations in liquid gasoline were also measured. Acetone and MEK were the most abundant carbonyls in unburned gasoline; eight other carbonyls were detected and quantified.

Air Pollutants↗
PubMed2004

Formation of secondary organic aerosol by reactive condensation of furandiones, aldehydes, and water vapor onto inorganic aerosol seed particles.

Volatile furandiones and aldehydes are significant atmospheric oxidation products of aromatic compounds. The mechanism of secondary organic aerosol formation by these compounds was probed using particle chamber observations and macroscale simulations of condensed phases. Growth of inorganic seed aerosol was monitored in the presence of humidity and high concentrations of 2,5-furandione (maleic anhydride), 3-methyl-2,5-furandione (citraconic anhydride), benzaldehyde, and trans-cinnamaldehyde. Particle growth commenced when the gas-phase saturation level of each organic compound and water vapor (relative to its pure liquid), when summed together, reached a threshold near one, implying the formation of a nearly ideal mixed organic/aqueous phase. However, these organics are immiscible with water at the high mole fractions that would be expected in such a phase. Highly acidic dicarboxylic acids produced by the reactions between furandiones and water were shown to rapidly acidify an aqueous phase, resulting in greatly increased benzaldehyde solubility. Thus, the uptake of these organics onto particles in the presence of humidity appears to be reaction-dependent. Finally, it is shown that dicarboxylic acids produced in these reactions recyclize back to furandiones when subjected to normal GC injector temperatures, which could cause large artifacts in gas/particle phase distribution measurements.

Aerosols↗