Carbonyl Compounds In Air Research Articles

Pentafluorophenylhydrazine as a coating reagent for the HRGC-MS determination of semi-volatile carbonyl compounds in air

Sensitive detection of semi-volatile carbonyl compounds in air can be achieved by using pentafluorophenylhydrazine-coated (PFPH) silica cartridges. Hydrazones formed during sampling are extracted with dichloromethane-acetonitrile and analysed by GC-MS operated in selected-ion-monitoring mode (SIM). The low detection limits reached (∼20 ppt (v/v) for sampling periods of 1 h) makes this method a valid alternative to other HPLC-UV and HRGC-MS techniques recently developed. Several experimental variables, for example collection and derivatization efficiency, interference by ozone, and storage stability of blank and sampled cartridges, have been investigated. Comparison field tests with the classical dinitrophenylhydrazine (DNPH) method showed results to be very consistent for C4–C11 n-alkanals and 6-h sampling periods during which six PFPH cartridges were run in parallel (each for 1 h) with one 2,4-dinitrophenylhydrazine (DNPH)-coated cartridge.

Determination of carbonyl compounds in air by electrochromatography.

A new analytical procedure based on electrochromatography was developed for the separation and quantitation of 14 aldehydes and ketones (formaldehyde, acetaldehyde, acetone, acrolein, propionaldehyde, butanone, crotonaldehyde, isobutyraldehyde/butyraldehyde, 2-pentenaldehyde, isovaleraldehyde, valeraldehyde, benzaldehyde and hexanaldehyde) in ambient air currently to be regulated by the Hong Kong Environmental Protection Department. A volatile mobile phase using ammonium acetate compatible with mass spectrometry detection was developed and optimized as follows. Methanol: acetonitrile: aqueous buffer (4 mM ammonium acetate) = 65:5:30% v/v. With electrokinetic injection at 5 kV for 2 s, aqueous buffer pH adjusted to 8, applied voltage controlled at 25 kV, and detection at 360 nm in a fused-silica column packed with 3 microm ODS, a satisfactory separation was obtained for the 14 carbonyl compounds investigated. The working ranges in acetonitrile solution were found to vary from 0.25 to 79 mg/L with a correlation coefficient greater than 0.99, detection limits from 0.10 to 0.63 mg/L, and precision (relative standard deviation, n = 3) from 2.3 to 9.2%. Under an air flow rate of 0.3 L/min for a sampling time of 1 h, the working ranges varied from 0.030 to 11,000 microg/m3 and detection limits from 0.011 to 0.084 microg/ m3. The method has been successfully applied to monitor three carbonyl compounds in four urban and rural sites in Hong Kong and gave hourly readings of three carbonyl compounds for all the sites investigated with a separation time less than 25 min.

Determination of aldehydes and ketones in air samples using cryotrapping sampling

A cryotrapping sampling technique using glass traps cooled in liquid nitrogen for monitoring carbonyl compounds in air has been developed. Sampling was followed by derivatization by addition of acidified 2,4-dinitrophenyl hydrazine (DNPH) solution to the traps and an aliquot of the sample was analysed with a high performance liquid chromatograph system (HPLC), equipped with a diode array detector. The procedure was optimised concerning derivatization conditions and analytical parameters on formaldehyde, acetaldehyde, propanal, acetone, butanal and benzaldehyde. The technique was applied in monitoring their concentration in the urban atmosphere in Ljubljana.

Rhodium-Catalyzed Conjugated Addition of Aryllead Reagents to α,β-Unsaturated Carbonyl Compounds in Air and Water

Rhodium-Catalyzed Conjugated Addition of Aryllead Reagents to α,β-Unsaturated Carbonyl Compounds in Air and Water

Dynamic system for the calibration of semi-volatile carbonyl compounds in air

A dynamic calibration system designed for generating accurate and precise concentrations of semi-volatile carbonyls in the ppb (v/v) (ppbv)−ppt (v/v) (pptv) range has been developed and tested. Alkanals from C 6 to C 9 were used as test compounds. Diffusion rates of their vapours from capillary tubes were determined theoretically and with two methods whose accuracy was independently evaluated with liquid standard solutions. Methods selected for testing the calibration system were those commonly used for the selective quantification of carbonyls in air. One is based on the well-known reaction with 2,4-dinitrophenylhydrazine (DNPH), followed by the analysis of formed hydrazones by HPLC-UV. The other is based on the retention of carbonyls on graphitic carbon adsorbents, followed by MS detection of the sample injected into a capillary column by thermal desorption. A good consistency was found between the values of the diffusion rates determined by the two methods. The scatter between the two methods was in the range of ±10% when diffusion rates of ca. 1 ng/s were attained. Experimental values closely approached those calculated by applying the equation describing the diffusion of a vapour in equilibrium with the liquid through a capillary tube.

The determination of carbonyl compounds in air using a robotic sampling preparation system integrated to a gas chromatograph with a nitrogen-phosphorus detector.

A totally automated solid phase extraction gas chromatography procedure was developed for the sampling and analysis of carbonyl compounds in air. In this system, two PrepStation modules were used, one for the preparation and elution of 2,4-dinitrophenylhydrazine silica cartridges, and the other for air sampling. The sample collected by the sampling module was eluted to an autosampler vial in the PrepStation module and then transferred to the gas chromatograph for analysis via a robotic arm. The sampling module was modified to enable air sampling via an external pump. A typical run by this technique required 142 min, 100 min for air sampling and 42 min for the other operations, including a GC analysis time of 25 min. Recoveries of at least 85% were obtained for all compounds studied. The detection limits for formaldehyde, acetaldehyde and acetone were 2.2, 2.7 and 2.2 ppbv, respectively. All operations, including the conditioning of the cartridges, were performed without any intervention from the analyst.

Trace analysis of carbonyl compounds by liquid chromatography–mass spectrometry after collection as 2,4-dinitrophenylhydrazine derivatives

This study describes the utilization of carbonyl-2,4-dinitrophenylhydrazine (DNPH) derivatives for the determination of a micro amount of carbonyl compounds in air by liquid chromatography–mass spectrometry (LC–MS). After the carbonyl compounds are collected using a Waters Sep-Pak C 18 cartridge column with impregnated DNPH on octadecylsilica, they are eluted by acetonitrile as carbonyl–DNPH derivatives. A 20-mm 3 aliquot of eluent is injected into the LC–MS system. The four derivatives (formaldehyde-, acetaldehyde-, acrolein- and acetone–DNPH) were eluted within 7 min with acetonitrile–water (60:40, v/v) as the mobile phase. The proposed method offers sub-ppb sensitivity and good reproducibility and was applied to the determination of these carbonyl compounds in actual air samples from store rooms, laboratories and offices. The relative standard deviations for these samples ( n=6) were 1 to 3%.

Use of C 18 and silica-gel coated Sep-Pak cartridges for the determination of carbonyls in air by liquid chromatography

C 18 and silica-gel cartridges coated with 2,4-dinitrophenylhydrazine (2,4-DNPH) were compared for the determination of formaldehyde, acetaldehyde, acetone, propionaldehyde and butyraldehyde levels from ambient air. Liquid chromatography (LC) was used for the analysis, and clear differences were found for acetone retention on each type of coated cartridge. Moreover, double peaks of acetaldehyde were observed in LC analysis from samples simultaneously collected in both impregnated C 18 and silica-gel cartridges. By using a KI filter during sampling to avoid ozone interference, retention and analysis were improved for some relevant carbonyl compounds in air. 2,4-DNPH silica-gel cartridges were used to determine carbonyls in ambient air from `Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas' (CIEMAT), located in Madrid surroundings.

Automated solid-phase extraction and coupled-column reversed-phase liquid chromatography for the trace-level determination of low-molecular-mass carbonyl compounds in air

This study reports the development of a coupled-column RPLC method for the trace level determination of several volatile aldehydes in ambient air. Carbonyls in air are sampled using a ozone scrubber and SPE C 18 cartridges which are pretreated with 2,4-dinitrophenylhydrazone. The method is used for the separation of 13 different aldehydes and ketones. All analytes are separated without high blanks or ozone interferences. The analytical detection limits for most important compounds formaldehyde, acetaldehyder, 2-propenal (acroleine), 2-butenal (crotonaldehyde( and benzaldehyde, range from 50 to 150 ng/m 3 (ppt) or 0.5–1.0 pmol/l, with relative standard deviations of 6%. The sampled air volume was 200 1. Due to the high sensitivity of the method, high purity solvents must be used. The analytical method as described below, has high recoveries for all analytes ( >90%) and is fully automated. this procedure has been applied in a pilot study with 60 air samples.

Analysis of reactive carbonyls in the expired air of transgenic mice

Methods for the determination of trace levels of volatile carbonyl compounds in air expired from mice were developed and validated. Tumor bearing transgenic mice or nontransgenic control mice were placed into a glass chamber through which air was passed continuously at 90 ml/min for 1 h. The effluent gas stream was bubbled into an aqueous cysteamine solution or an aqueous methylhydrazinesolution. Formaldehyde, acetaldehyde, and acetone in expired air were derivatized to thiazolidines with cysteamine and malonaldehyde was derivatized to 1-methyl-2-pyrazole with methylhydrazine. The derivatized compounds were analyzed by capillary gas chromatography with flame photometric or nitrogen-phosphorous-specific detection. The lowest level quantitated was 4 μg/ml thiazolidine, equivalent to 1.35 μg/ml formaldehyde. Formaldehyde was recovered at a level of 1356 ± 234 nmol/kg 0.75 (mean ± SD) from mice with tumors and 898 ± 97 nmol/kg 0.75 from mice without tumors, suggesting that tumor bearing transgenic mice expired significantly more formaldehyde than did tumor free controls. Amounts of expired acetaldehyde and acetone were not different among mice. Malonaldehyde was not detected in either group of mice.

Determination of carbonyl compounds in air by HPLC using on-line analyzed microcartridges, fluorescence and chemiluminescence detection

Sensitive and selective detection of dansylhydrazones of atmospheric carbonyl compounds (aldehydes and ketones) can be achieved using high performance liquid chromatography (HPLC) with fluorescence or chemiluminescence detection. The carbonyl compounds are derivatized by drawing air through small glass cartridges packed with porous glass particles impregnated with dansylhydrazine. After sampling, the contents of the cartridges are analyzed on-line by using a small plug of water (200 μL) to transfer and focus the hydrazone derivatives at the head of a HPLC column. Greatly increased sensitivity over traditional methods derives from 1) analysis of the entire contents of the sampling cartridge, and 2) detection by fluoresence or peroxyoxalate chemilum-inescence. Results are compared for photo-initiated and H2O2-initiated peroxyoxalate chemiluminescence. This novel and practical system enables the detection of sub-ppbv concentrations of formaldehyde, acetaldehyde, acetone and higher carbonyls in air using relatively short sampling times.

Quantitative determination of carbonyl compounds in rendering emissions by reversed-phase high-performance liquid chromatography of the 2,4-dinitrophenylhydrazones

A simple and rapid method for the determination of volatile carbonyl compounds in air has been developed. The method is applied to the quantitation of C1–C9 aldehydes and acetone in rendering emissions.Carbonyl compounds are sampled by absorption in a 2 × 10–4M 2,4-dinitrophenylhydrazine solution at pH 1 and the resulting hydrazones are extracted with 2,2,4-trimethylpentane, concentrated and analysed by HPLC on a 10-µm RP-C18 column with a water - acetonitrile gradient as the eluent. The hydrazones are then spectrophotometrically detected at 356 nm. The micro-scale conversion of carbonyls into 2,4-dinitrophenylhydrazones is investigated, the separation of hydrazones is improved and the sampling conditions are tested in order to achieve quantitative sampling at an air flow rate of 1 l min–1. Quantitation is possible for concentrations as low as 15 p.p.b. (formaldehyde) and 2 p.p.b. (nonanal). The over-all coefficient of variation (taken over sampling, conversion and analyses) is less than 10%.

Trace determination of carbonyl compounds in air by gas chromatography of their 2,4-dinitrophenylhydrazones

Trace determination of carbonyl compounds in air by gas chromatography of their 2,4-dinitrophenylhydrazones