Ozone measurement with silica cartidges and HRGC-MS analysis

Ozone in ambient air is collected onto silica gel cartridges impregnated with pentafluorophenylhydrazine (PFPH) and 1,2-di(4-pyridyl)ethylene (DPE), so that the pyridine-4 aldehyde formed by DPE oxidation is converted into the corresponding PFPH derivative (PPH). The latter product is determined by HRGC/MS. Since the ozonolysis reaction proceeds stoichiometrically on the cartridge, there is no need for calibration in the gas phase with a standardized ozone source. When compared with UV photometry analyzers, this active chromatographic method (ACM) demonstrates a very good accuracy (ACM/UV photometer = 0.97) and precision (12.0-14.0%) under both laboratory and field sampling conditions at ozone concentrations of 20-200 microg m(-3) and exposure times of 1-3 h. The sampling performance was found to be insensitive to relative humidity (r.h.) variations in the 25-90% range and any interference effects could not be observed from various agents, except light, which can be eliminated by using an aluminium shelter. The detection limit for ozone achievable with the ACM in air samples collected at 0.5 L min(-1) for 1 h was found better than 0.5 microg m(-3).     

A specific spectrophotometric determination of ozone in air in the presence of sulfur dioxide and nitrogen oxides

A sensitive, specific spectrophotometric method for the determination of ozone in air by the ozonolysis of 1,1-di-phenylethylene (DPE) is described. The yield of formaldehyde from the ozonolysis of several terminal olefins was determined, and DPE was found to give the highest yield, 90%. The method was checked against the EPA iodimetric method, and gives a consistent yield of formaldehyde over the ozone range 0.05–5.00 μg g^-1 of air. As sulfur dioxide is used as a reagent, its presence in air does not interfere. Interference by nitrogen oxides and other free radical oxidants is prevented by the addition of mesitol (2,4,6-trimethylphenol). Formaldehyde in air interferes, but can be determined by using the method with DPE omitted from the sampling train, and so accounted for. In the procedure, formaldehyde is determined by the reverse of the West—Gaeke method for sulfur dioxide.     

Determination of gaseous carbonyl compounds by their pentafluorophenyl hydrazones with gas chromatography/mass spectrometry

A sensitive and reliable method has been developed for the simultaneous determination of 20 airborne carbonyl compounds in the C₁-C₁₀ range. The carbonyls were collected onto solid sorbent coated with pentafluorophenyl hydrazine (PFPH), followed by solvent extraction and gas chromatographic (GC)/mass spectrometric (MS) analysis of the PFPH derivatives. The sorbent is packed into two separate sections in a glass sampling tube. The two-section design allows convenient checking of collection efficiency and breakthrough. The sampling tube, with a coating amount of 971 nmol PFPH per 100 mg Tenax TA and operated at a sampling flow rate of 80 mL min⁻¹, collects the 20 carbonyls with efficiencies above 95%. Hexane extracts the collected carbonyls in their PFPH derivatives in the sampling tube with better than 95% extraction efficiency. It is necessary to let the sampling tube sit at ambient temperature for 3 days before solvent extraction to ensure complete derivatization of the carbonyls. The limits of detection (LODs) of the tested carbonyls are in the range of 3.7-11.6 ng per sample. The method has been field-tested both in ambient environment and in an indoor environment from burning mosquito-repellent incense. Eighteen carbonyls were detected in the ambient air samples with the exception of o-tolualdehyde and m-tolualdehyde, while all the 20 target carbonyls were found in the incense smoke. Compare field test with classical DNPH-HPLC/UV method, good agreement exited between the two methods for lower molecular carbonyls but PFPH method is found to be a better analytical method for determination of high molecular weight carbonyls.     

A versatile and uncomplicated method for the analysis of volatile organic compounds in ambient urban air

A method was developed for sampling and selective quantitative determination of typical volatile organic compounds (VOCs) in ambient urban air. A mobile and self-contained dual-channel air sampling tool based on solid phase adsorption was constructed. A simple calibration procedure circumventing the adsorption/desorption process was designed. The method was validated for seven “key-analytes”: n-hexane, 3-methyl-2-pentene, benzene, tetrachloroethene, styrene, 1,2,4-trimethylbenzene and acetophenone. The complete air sampling equipment is easily accommodated in a business suitcase. The lower limits of the practical working ranges are between 0.1 μg m^–3 (tetrachloroethene) and 1.2 μg m^–3 (benzene). Air samples were collected at a location in Salzburg with heavy motor vehicle traffic and measured in order to prove a satisfactory method performance under practical monitoring conditions.     

Application of passive sampling technique in monitoring research on quality of atmospheric air in the area of Tczew,Poland

This paper presents the results of atmospheric air quality research in Tczew (adjacent to the Vistula River) on the content of BTEX compounds. procedure applied during the sampling of the analytes from the air used the passive sampling technique (diffusive passive sampler, Radiello^®). For determination of BTEX compounds in atmospheric air, two-stage thermal desorption technique combined with gas chromatography (TD-GC-FID) was applied.

Research was conducted from March to December 2011. The annual average concentration of benzene, toluene, ethylbenzene and total xylenes determined in atmospheric air for the monitoring period were: 0.87 μg m^–3, 2.9 μg m^–3, 1.3 μg m^–3 and 5.9 μg m^–3, respectively. In order to pre-identify potential sources of emissions of BTEX compounds, statistical analysis was carried out. This determined interactions between specified concentration levels of BTEX compounds in atmospheric air for the monitored area.     

Design of air quality monitoring networks and its application to NO2 and O3 in Cordova, Spain

Air monitoring networks are necessary to assess air quality in order to reduce pollution to levels which minimise harmful effects on human health and the environment. This paper describes a method to design air quality monitoring networks for nitrogen dioxide and ozone and its application in Cordova, Andalusia, southern Spain. The city has a population of 325,453 inhabitants and traffic is its main source of air pollution. The first step of this method made it possible to determine from historical data that two control stations for NO₂ and one control stations for O₃ are necessary according to the legislation. Sampling campaigns with passive diffusion samplers at 81 sites were then carried out to obtain information on the pollution distribution in Cordova. The sampling campaigns in 2001–2002 revealed an average concentration of 19.5 μg/m³ for NO₂ with maximum values up to 28.6 μg/m³ in Cordova city centre. The average ozone concentrations were recorded downwind from the emission source, reaching 91.8 μg/m³; the average ozone value in Cordova was 65.3 μg/m³. After spatial interpolation of the obtained values with Geographical Information Systems, a selection of the best locations for the monitoring stations was made, in line with the macro- and microscale siting requirements of the European Directive 2008/50/EC on ambient air quality and cleaner air for Europe. A second sampling campaign with diffusive samplers was carried out in 2007 to control if the locations of the air quality assessment stations were still representative for their zone.     

Quantification of transformation products of rocket fuel unsymmetrical dimethylhydrazine in air using solid-phase microextraction

Quantification of unsymmetrical dimethylhydrazine transformation products in ambient air is important for assessing the environmental impact of heavy rocket launches. There are very little data of such analyses, which is mainly caused by the low number of analytes covered by the available analytical methods and their complexity. A simple and cost-efficient method for accurate simultaneous determination of seven unsymmetrical dimethylhydrazine transformation products in air using solid-phase microextraction followed by gas chromatography-mass spectrometry was developed. The method was optimized for air sampling and solid-phase microextraction from 20-mL vials, which allows full automation of analysis. The extraction for 5 min by Carboxen/polydimethylsiloxane fiber from amber vials and desorption for 3 min provided the greatest analytes' responses, lowest relative standard deviations, linear calibration (R² ≥ 0.99), and limits of detection from 0.12 to 0.5 μg/m³. Samples with concentrations 500 μg/m³ can be stored at 21 ± 1°C without substantial losses (1–11%) for up to 24 h, while air samples with concentrations 10 and 50 μg/m³ stored for up to 24 h can be used for accurate quantification of only two and four out of seven analytes, respectively. The developed method was successfully tested for the analysis of air above real soil samples contaminated with unsymmetrical dimethylhydrazine rocket fuel.     

Comparison of passive and active sampling methods for the determination of nitrogen dioxide in urban air

Three different methods for sampling and determination of nitrogen dioxide in urban air are compared: an NO/NO_x-monitor and an active (pumped) and a passive sampling method. For the latter two methods, sodium iodide is used as absorbent. For weekly averages the results from the passive sampler are within 10–20% of the results for the two other methods in the concentration range 15–30 μg NO₂/m³. The detection limit for the passive sampler is 1 μg NO₂/m³ (7 days), the precision is 5% and the accuracy is estimated to 20%. The active iodide method agrees very well with the NO/NO_x-monitor. Compared on 24 h basis for a period of 3 months, covering a concentration range of 5–45 μg NO₂/m³, the deviation between the two methods is within 5%, and the absorption capacity of the iodide reagent is excellent as the breakthrough is below 1%.     

Stepwise injection photometric determination of nickel in air aerosols

A procedure is developed for the automated determination of nickel in air aerosols; it involves the adhesive separation of aerosols on a fiberglass column in the on-site mode followed by the photometric determination of analytes with dimethyl glyoxime under the conditions of stepwise injection analysis of aerosol concentrates. The analytical range for nickel is 1.5–38 μg/m³; the detection limit of the method is 0.5 μg/m³ at an air sample volume of 30 L. The duration of sampling to an adhesive column and concentrate analysis were 15 and 10 min, respectively.     

The determination of free ammonia in ambient air with diffusion/denuder tubes

Ammonia is important in atmospheric chemistry because it neutralises acidic species and increases the pH of cloud droplets. Data on the concentration of free ammonia in the atmosphere are sparse because it is difficult to separate free ammonia from particulate ammonium salt aerosol. A manual method for the determination of free ammonia in air is described based on diffusion/denuder tube separation of ammonia from ammonium salt aerosol. When air is drawn through a tube coated with a selective absorbent (here oxalic acid) separation is achieved because the gaseous species diffuses much more rapidly to the tube wall than the particles. After the sampling period (usually 1–4 h, depending on the free ammonia concentration expected), the sorbed ammonia is washed from the tube and measured potentiometrically with an ammonia probe. The method is tested theoretically and experimentally. The absorption efficiency of the coated tubes is ca. 90%. In samples of room air containing 12–28 μg m^?3, the standard deviation is estimated as 1.0 μg m^?3. In field use, ammonia contents were in the range 0.53–5.0 μg m^?3.     

The determination of hydrogen chloride in ambient air with diffusion/denuder tubes

A manual method for the determination of hydrogen chloride in air, based on diffusion/denuder tube separation from particulate chloride aerosol is described. When air is drawn through a tube coated with a selective absorbent (sodium fluoride), separation is achieved because gaseous hydrogen chloride diffuses much more rapidly to the tube walls than particulate chloride aerosol, which passes through virtually unabsorbed. After the sampling period (the length of which depends on the concentration of gaseous hydrogen chloride expected), the sorbed hydrogen chloride is washed from the tube and measured with a highly sensitive chloride ion-selective electrode with a mercury (I) chloride membrane. The method is examined theoretically and experimentally. The experimentally derived absorption efficiencies of the diffusion/denuder tubes were > 90% and the standard deviation of the method was 0.023 μg m^?3 for hydrogen chloride concentrations of 0.16–0.55 μg m^?3. Interference from particulate chloride salts was negligible; this was confirmed by tests with artificially generated aerosol particles from an aerosol generator. The diffusion/denuder tubes have high capacity; level as high as 330 μg m^?3 hydrogen chloride can be sampled for 60 min without affecting performance. A detection limit of (50/t) μg m^?3 can be achieved, where t is the sampling rime (min); e.g., 1μg m^?3 hydrogen chloride can be detected with a sampling period of 50 min.     

A sensitive,specific method for the determination of tetraalkyllead compounds in air by gas chromatography/atomic absorption spectrometry

The development of a sensitive and specific method of determining individually the five tetraalkyllead compounds normally present in ambient air is described. The method is based on collection of the analytes on a porous polymer using a prefilter to destroy ozone and prevent decomposition of the sample during collection and storage. Two-stage thermal desorption, separation by gas chromatography and detection by modified flame atomic absorption spectrometry gives detection limits (3σ) of ca. 0.25 ng Pb m^?3 for tetramethyllead and 0.37 ng Pb m^?3 for tetraethyllead in an air sample of 80 dm³ collected over a 3–24 h period. Environmental sampling by this method in paralle with a wet chemical (iodine monochloride) method was used to validate the method. During the comparative study, higher organic lead levels were consistently found by the iodine monochloride method; it is postulated that this indicates the presence of vapour-phase tri-(or di)-alkyllead in excess of 1 ng Pb m^?3 in rural air. The versatility of the method is demonstrated by the results of atmospheric sampling at two locations, one rural and one at the kerbside in a city centre.     

Optimization of the design of air quality monitoring networks and its application to NO2 and O3 in Jaen,Spain

The assessment of air quality is necessary in order to control and reduce pollution to levels which minimise harmful effects on human health and the environment. This paper describes a method to design air quality monitoring networks for nitrogen dioxide and ozone and its application in Jaen (southern Spain). A fibre-glass filter impregnated with triethanolamine was used in diffusive sampling badges for NO₂ determination. For O₃ analysis, sodium nitrite was selected and nitrate, a product of the reaction of ozone and nitrite, was used to assess the ozone concentrations. Sampling campaigns with passive diffusion samplers at 62 sites were then carried out to obtain information on the pollution emissions in Jaen. The sampling campaigns in 2001–2002 revealed an average concentration of 10.4 μg/m³ NO₂ with maximum values up to 22.5 μg/m³ in Jaen City centre. The average ozone concentrations were recorded downwind from the emission source, reaching 96.2 μg/m³; the average ozone value in Jaen was 72.0 μg/m³. After spatial interpolation of the obtained values with Geographical Information Systems, a selection of the best locations for the monitoring stations was made, in line with the macro- and microscale siting requirements of the European Directive 2008/50/EC on ambient air quality and cleaner air for Europe. A second sampling campaign with diffusive samplers was carried out in 2005–2006 to control if the locations of the air quality assessment stations were still representative for their zone.     

Determination of trace-metal concentrations in size-classified atmospheric particles by ETV-ICP-MS

Atmospheric particles were sampled and fractionated according to their size by a cascade impactor in Berlin, capital city of Germany, on the Brocken, peak of the Harz mountains and on the Szrenica peak in the Giant mountains, Republic Poland. The fractionated particles were collected on small graphite targets and subsequently analyzed by ETV-ICP-MS. Distribution curves were measured showing trace-metal contents in air versus the aerodynamic particle diameter for the elements Pb, Ag, Cd and Tl. Despite good element correlation, the distribution curves differ significantly for the three sampling locations. The limits of detection for the elements of concern were in the pg/m³ range at a sampling time of 4 h. An attempt was made to determine single particles: in urban aerosols a content was found of 1 · 10^–13 g Tl and 9 · 10^–13 g Ag in single particles of the size fraction < 7.5 μm and > 3.45 μm.     

Quantitative Determination of Formaldehyde In Air Using the Acetylacetone Method

Abstract

The quantitative determination of formaldehyde in air using the fluorimetric acetylacetone method is described. Known concentrations of formaldehyde were generated and collected in water using abosorbers. The sampling rate was 0.5 1/min, and the sampling volumes varied from 2 to 20 1, depending on the concentration level. Under these conditions the entire sampling and the analytical method were evaluated over a range of 0.2–1.7 mg formaldehyde per m³ of air.

The precision of the method expressed as a mean value of the relative standard deviation of 7 independent measurements (6 single determinations each) was (3.4 ± 1.6) % (SD). The accuracy was (101 ± 5) % (SD). The detection limit of the method was estimated to be 0.040 mg formaldehyde per m³ of air (5 liter air sample).     

Determination of N-Nitroso Compounds in the Environment of a Metal Factory Using Metalworking Fluids

Abstract

By use of GLC-ECD and HPLC-TEA techniques for N-nitroso compounds, N-nitroso-diethanolamine (NDELA) has been found in concentrations of 1.4–6.0 μg/m³ and 1.3–5.0μg/m³ respectively in all four air samples collected in the environment of a metalworking plant during metallurgical operations. NDELA was quantitated in air samples by GLC-ECD after converting it to its trifluoroacetyl derivative by reaction with the appropriate anhydride. NDELA was analyzed without derivatization in air samples using HPLC-TEA method. N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were also identified and later determined in two out of four air samples in concentrations of 0.08μg/m³ (for NDMA in both samples) and 0.14–0.16μg/m³ (for NDEA) using GLC-TEA procedure. The described method did not cause artifactual formation of N-nitrosomethyl-N-butylamine (NMBA) when methyl-N-butylamine was used as an internal marker of nitrosation during collection of NDELA in impinger traps.     

Analysis of t-Butyldimethylsilyl Derivatives of Chlorophenols in the Atmosphere of Urban and Rural Areas in East of France

A method using GC-MS and derivatization with N-(t-butyldimethylsilyl)-N-ethyltrifluoroacetamide (MTBSTFA) was developed for the analysis of 19 chlorophenols compounds in atmospheric samples (gas and particles). Air sampling was carried out using a Hi-Vol sampler with glass fibre filter and XAD-2 resin at a flow rate of 60 m³ h⁻¹. The particle and gas phases were collected separately over a period of 4 h. Samples were Soxhlet extracted, evaporated to dryness under nitrogen and refilled with acetonitrile. 100 mL of these extracts were derivatized with 100 μL of MTBSTFA at 80 °C for 1 h under strong stirring. Sylylated chlorophenols were injected into a GC-MS in splitless mode and quantified as their TBDMS derivatives in the SIM mode. Mass spectral analysis of the derivatives of the 19 compounds studied indicates that the spectra are highly specific showing an ion at [M - 57]⁺ which is useful for structure confirmation or analysis at low levels using selected ion monitoring. Quantification limits varied between 5 μg L⁻¹ and 10 μg L⁻¹ which correspond to 20 pg m⁻³ and 40 pg m⁻³ for 250 m³ of air sampled. This method was successfully applied to atmospheric samples collected simultaneously in winter 2004 in an urban (Strasbourg) and rural (Erstein) areas in east of France.     

Determination of Methylamines and Methylamine-N-oxides in Particulate Matter Using Solid Phase Extraction Coupled with Ion Chromatography

Currently, the concentrations of methylamines in fine particulate matter (PM) are most often measured by aerosol time-of-flight mass spectrometry. A novel method for identification and determination of methylamines and methylamine-N-oxides in fine particles based on solid phase extraction (SPE) coupled with ion chromatography (IC) was developed. The experimental conditions including SPE conditions and chromatographic conditions were optimized. The quartz filter loaded with particulate matter (PM) samples was ultrasonically extracted with 20 mL of methanol and water (1:3, V/V) and the extraction process was repeated twice. After extraction, a total of 60 mL of extraction solvent was dropped into the extraction equipment for SPE. The Agilent AccuBond C₁₈ was chosen for enriching the methylamine, dimethylamine, trimethylamine and trimethylamine-N-oxide in fine particles. Under the optimum conditions, the target species on Agilent AccuBond C₁₈ were washed by 0.5 mL of acetonitrile solution and then concentrated (2 mL) before injecting into IC for analysis. A PRP X-200 (250 mm × 4 mm i.d.) was used for separation of analytes at 25 °C. The mobile phase was a mixture of 3% (V/V) acetonitrile solution and 5 mM nitric acid with the flow rate of 1 mL min^–1. The four aliphatic amine species were fully resolved and completely separated within 30 min. The linearity of the four compounds ranged from 0.45 μg kg^–1 to 1000 μg kg^–1 with precisions of 2%–4% and detection limits of 0.002–0.003 μg m^–3. The recoveries of the four aliphatic amine species in real PM samples were higher than 90%. This method was successfully applied in the analysis of real fine PM samples collected in Beijing. The concentrations of trimethylamine and methylamine-N-oxides were in the range of (0.01 ± 0.001) μg m^–3–(0.08 ± 0.002) μg m^–3 and (0.05 ± 0.001) μg m^–3–(0.14 ± 0.002) μg m^–3 for Beijing dust and haze PM samples, respectively.     

A new ozone denuder for aerosol sampling based on an ionic liquid coating

A new ionic liquid 1-octyl-3,5-dimethylpyridinium iodide ([O35LUT]⁺[I]⁻) was synthesized and utilized as coating for an ozone denuder device based on a high-volume aerosol sampler (30 m³ h⁻¹). Particle transmission of the denuder was studied, and over 99% of particles ranging from 10 to 2,500 nm were transmitted. The device, containing 4.66 g of ionic liquid, was used outdoors, under dry and damp atmospheric conditions. In order to expose the device to an average concentration of 120 ppbv (240 μg m⁻³) of ozone in air, an additional production of ozone was directly injected into the denuder. Under these conditions, over 97% of ozone was removed for approximately 120 h (5 days). Therefore, iodide-based ionic liquids can be used as a new alternative to conventional denuder coatings in order to reduce artifacts occurring during sampling of particulate matter. Future applications are not limited to ozone removal for specific aerosol sampling methods.     

Atmospheric Hydrocarbon Concentrations in the Baltic Sea Area

Abstract

During a marine research expedition in 1983 in the Baltic Sea area air samples were collected for the analysis of several organic and inorganic pollutants. The aim of the expedition was to obtain information on the airborne load in the sea as well as to measure the concentrations of the pollutants far away from source areas. In this paper the background concentrations of the primarily traffic originated aromatic hydrocarbons benzene, toluene and xylenes will be presented.

The concentrations of benzene were from 0.2 to 2μg/m³, of toluene between 0.4–3μg/m³, of m-xylene 0.02–0.60μg/m³ while the concentrations of o-xylene were 0.01–0.1 μg/m³. The concentrations did not depend too much on the origin (continental/sea type) of the air masses. A weak minimum in the concentrations of the measured hydrocarbons was noticed in the central Baltic Sea area. When comparing lead concentrations in fine particles (< 2.5 μm) with those of benzene, toluene and m-xylene some coincidence between them could be observed.