Air sampling of organophosphate triesters using SPME under non-equilibrium conditions

Solid phase micro-extraction (SPME) was used to collect air samples of semi-volatile organophosphate triesters, a group of compounds that are commonly used as flame retardants/plasticisers and have therefore become ubiquitous indoor air pollutants. SPME is a simple sampling technique with several major advantages, including time-efficiency and low solvent consumption. Analyte losses also tend to be relatively low. In quantitative SPME, measurements are normally taken after the analyte has reached partitioning equilibrium between the fibre and the sample matrix. However, equilibrium sampling of semi-volatile compounds in air with SPME often takes several hours. Clearly, time-weighted average (TWA) sampling using SPME under non-equilibrium conditions could be considerably faster. So, in this study, the possibility of sampling organophosphate triesters under non-equilibrium conditions was tested. The most important variables proved to be the fibre coating and the air velocity during sampling. The highest uptake rate was obtained with polydimethylsiloxane (PDMS, 100 m). The rate for this fibre was 150-fold higher than obtained with PDMS/DVB and Carbowax/DVB, both 65 m. Contrary to theoretical expectations, the uptake rate appeared to be constant for all tested air velocities over the fibre surface >7 cm/s. These findings suggest that the uptake rate for non-equilibrium SPME sampling is independent of the sampling flow above this flow rate, which would considerably enhance the robustness and flexibility of the method. Applying this method for TWA sampling, with sampling periods of 1 h, detection limits lower than 2 ng/m³ for individual organophosphate esters were obtained.     

Evaluation of solid-phase microextraction with PDMS for air sampling of gaseous organophosphate flame-retardants and plasticizers

As an inexpensive, simple, and low-solvent consuming extraction technique, the suitability of solid-phase microextraction (SPME) with polydimethylsiloxane (PDMS) sorbent was investigated as a quantitative method for sampling gaseous organophosphate triesters in air. These compounds have become ubiquitous in indoor air, because of their widespread use as additive flame retardants/plasticizers in various indoor materials. Results obtained by sampling these compounds at controlled air concentrations using SPME and active sampling on glass fibre filters were compared to evaluate the method. A constant linear airflow of 10 cm s^–1 over the fibres was applied to increase the extraction rate. For extraction of triethyl phosphate with a 100-m PDMS fibre, equilibrium was achieved after 8 h. The limit of detection was determined to be less than 10 pg m^–3. The PDMS–air partition coefficients, K_fs, for the individual organophosphate triesters were determined to be in the range 5–60×10⁶ at room temperature (22–23°C). Air measurements were performed utilising the determined coefficients for quantification. In samples taken from a lecture room four different airborne organophosphate esters were identified, the most abundant of which was tris(chloropropyl) phosphate, at the comparatively high level of 1.1 g m^–3. The results from SPME and active sampling had comparable repeatability (RSD less than 17%), and the determined concentrations were also similar. The results suggest that the investigated compounds were almost entirely associated with the gaseous phase at the time and place sampled.     

The Use of a Thin Glass-Ceramic Rod as a Surface for Sol-Gel Coating in the Preparation of SPME Fibers

The efficiency of a glass-ceramic rod as a base for the preparation of SPME fibers using sol-gel technology was investigated. Glass-ceramic rod was coated with PDMS using sol-gel reaction, and its surface characteristic was determined for SEM. Optimum conditions for the preparation of the fiber are presented. The same procedure was used for coating the fused silica rod. The fibers thickness and absorption capacity were compared. The proposed fiber was used for the extraction of a mixture of BTEX, from aqueous samples. The results obtained proved the superiority of glass-ceramic as a new base for SPME fiber, resulting in a thickness of ~44 m against 6 m for fused silica base. The calibration graphs for BTEX were linear (r > 0.998) and the detection limits were below 0.8 g L^–1.     

Gas-chromatographische Analyse von Kohlenwasserstoffen in der Au?enluft nach Probenahme mit dem Tieftemperaturgradientenrohr

Zusammenfassung Es wird über ein gas-chromatographisches Verfahren zur Bestimmung von Alkanen, Alkenen und Aromaten in der Außenluft berichtet, bei dem die Probenahme an Tenax GC oder Carbopack mit Hilfe eines Tieftemperaturgradientenrohres erfolgt und die Analyse unter Einsatz eines Doppelsäulensystems in Verbindung mit zwei Flammenionisationsdetektoren durchgeführt wird. Eingehende Untersuchungen zum Verhalten der Substanzen bei der Probenahme zeigen, daß die Trocknung der Probeluft mit Magnesiumperchlorat das Ergebnis nicht beeinflußt und für Kohlenwasserstoffe mit drei oder mehr C-Atomen keine auf Durchbruch zurückzuführenden Substanzverluste zu befürchten sind. Bei einem Probenahmevolumen von 51 Luft können 2 g Substanz/m³ gut bestimmt werden. Für Außenluft-Konzentrationen von 45 g Benzol/m³, 95 g Toluol/m³ und 35 g n-Pentan/m³ betrugen die Standardabweichungen 3,5, 6,0 bzw. 3,6 g/m³. Bei leichter Modifikation des Systems ist mit derselben Probenahmevorrichtung die gleichzeitige Bestimmung von Kohlenwasserstoffen mit einem Flammenionisationsdetektor und von Organohalogen Verbindungen mit einem Elektroneneinfangdetektor möglich.

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Gas-chromatographic analysis of hydrocarbons in ambient air with cryogenic sampling

Summary A method is described for the gas-chromatographic determination of alkanes, alkenes and aromatics in ambient air. The hydrocarbons are trapped by cryogenic sampling using Tenax GC or Carbopack as adsorbing material and are analyzed in a two-column system equipped with two flame-ionization detectors. A detailed examination of the sampling procedure shows that drying the air with magnesium perchlorate does not affect the results, and losses of substances due to break-through need not be reckoned with for hydrocarbons with three and more carbon atoms. In a 51 air sample 2 g/m³ of hydrocarbons can be determined readily. The standard deviations for benzene, toluene and n-pentane were 3.5, 6.0 and 3.6 g/m³ at ambient air concentrations of 45, 95 and 35 g/m³. A slight modification of the system which includes the combined use of a flame-ionization detector and an electron-capture detector permits the simultaneous determination of hydrocarbons and halogenated hydrocarbons.

     

Passive sampling for volatile organic compounds (VOCs) in air at environmentally relevant concentration levels

A sensitive and reliable method is described for the determination of aromatic and chlorinated hydrocarbons (benzene, toluene, o-, m-, p-xylene, trichloromethane, trichloroethane, trichloroethene and tetrachloroethene) in indoor and outdoor air at environmental concentration levels. The procedure can be easily extended to other VOCs. Using passive samplers the VOCs have been adsorbed onto charcoal during a four-week sampling period and subsequently desorbed with carbon disulfide. After injection with a cold split-splitless multi-injector the VOCs have been separated by capillary gas chromatography. Quantification has been achieved using an electron capture detector (ECD) and a flame ionization detector (FID) switched in series. A limit of about 1 g/m³ for aromatic hydrocarbons and of about 0.01 g/m³ for chlorinated hydrocarbons has been obtained. The procedure has been successfully applied in the framework of a field study to measure indoor and outdoor air concentrations in Essen and Borken, two differently polluted areas of Northrhine-Westphalia.     

Preconcentration and determination of naphthalene in air and water using activated carbon adsorption,carbon disulfide extraction and gas chromatography

A new method for the determination of naphthalene in air and water has been developed. The naphthalene was preconcentrated using activated carbon adsorption with carbon disulfide extraction and determined by gas chromatography with flame ionization detection. The chromatographic peak of naphthalene was separated well from the potential interferents turpentine, terpenene, isoborneol, camphor and isobornyl acetate. The detection limit was 0.52 g/ml of CS₂, equivalent to 2.6 g/m³ of air or 0.05 g/ml in 50 ml of water. The precision for 10 g/ml naphthalene was 1.7%. The adsorption capacity, sampling efficiency and desorption efficiency of 100 mg of activated carbon for naphthalene in air were 8.8 mg, 98.8% and 95.2%, respectively. The extraction efficiency of 5 ml of carbon disulfide for naphthalene in water was 97.6%. The method was successfully applied to the determination of naphthalene in air and water from an industrial plant.     

Method comparison study on soot-selective techniques

In a long-term field study at two locations with different air pollution levels several soot-selective measurement techniques were compared with a thermochemical method which measures non-extractable carbon (NEC) detecting the evolved CO₂ by means of coulometric titration. The attenuation measurement technique (aethalometer) and the aerosol photoemission method showed good correlations to NEC for concentrations ranging from 1.6g/m³ to 40.8g/m³. The specific mass absorption coefficient of black carbon with respect to NEC varied between 8.4m²/g and 13.7m²/g with respect to the measurement sites, but the value was found to remain constant at each site independent of seasonal or meteorological variations. The ratio of photoelectric signal to NEC varied between 16 fA·(g/m³)^–1 and 33 fA·(g/m³)^–1 depending on the age of the aerosol. The diurnal variations of that ratio showed strong similarities to the traffic patterns. Additionally a slight temperature dependence of this ratio was found for the aged aerosol with a proportionality factor of – 0.35 fA·(K·g/m³)^–1. With the reflectance measurement technique (smoke shade method) reliable NEC determination was not possible for NEC concentrations 5 g/m³.     

Effects of meteorological conditions on outdoor radon daughters concentrations in Montreal

The concentration of radon daughters in outdoor air in Montreal was measured almost daily over a 1 year period from April 1988 to March 1989. The values measured displayed a mean of 1.2 mWL (0.25 J/m³), a median of 0.7 mWL (0.15 J/m³), a mode of 0.6 mWL (0.12 J/m³) and standard deviation of 1.2 mWL (0.25 J/m³). The concentrations increase with increasing temperature and with decreasing barometric pressure. They decrease with the amount of precipitation. Wind velocity had little effect on the concentrations.     

Detection of 2,4,6-trichloroanisole in chlorinated water at nanogram per litre levels by SPME–GC–ECD

A method involving solid-phase micro extraction (SPME) and gas chromatography with electron capture detection (SPME–GC–ECD) has been optimised for identification and quantification of 2,4,6-trichloroanisole (TCA) at ng L^–1 concentrations in disinfected (chlorinated) water samples. A central composite design was used for factorial analysis of four factors, three factors related to the SPME (PDMS fibre) procedure (adsorption time, temperature of the sample during headspace sampling, and desorption time) and one related to the GC operation (the rate of increase of the temperature of the GC oven). Good linearity (linear correlation coefficient greater than 0.999) was observed for TCA concentrations up to 50 ng L^–1, limits of detection and quantification of 0.7 and 2.3 ng L^–1, respectively, and good precision (relative standard deviation 2.8% and 3.4% for 5 and 30 ng L^–1 of TCA, respectively). Besides TCA, this system also enables the detection and quantification of the four trihalomethanes in the g L^–1 concentration range with limits of detection and quantification of approximately 0.3 g L^–1 and 1 g L^–1, respectively.     

Fluoridbestimrnung in Wasser und Luft mit ionenselektiven Elektroden

Zusammenfassung Systematische Bestimmungen des Fluoridgehaltes in verschiedenen Wasserproben aus Serbien und in Luftproben aus einigen In-dustriegebieten und aus der Stadt Belgrad wurden durchgeführt. Außerdem wurde der Fluoridgehalt in einigen meistkonsumierten Mineralwässern aus alien Territorien Jugoslawiens geprüft. Etwa 600 Proben wurden analysiert. Die Ergebnisse sollen für die kartographische Erfassung der Verteilung von Fluor im Trinkwasser dienen.

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Determination of fluoride in Yugoslavian air and water with an ion-sensitive electrode

Summary Fluoride has been measured in over 600 samples of air and water with an ion-sensitive electrode. The concentrations found in the air samples were 1.6–l08g/m³ for industrial areas, 1.9–25.6g/m³ for urban areas and 1.1–18.4g/m³ for rural areas. Most of the samples had fluoride levels below 20g/m³3. The concentrations found in water samples were 0.12–0.34g/litre for drinking water and 0.27–5.6g/litre, for mineral waters.

     

Production of96Tc and95mTc via the93Nb(α, xn) Reactions

Relatively longer liver technetium tracers such as^95mTc (61 d) are useful for the development, evaluation and comparison of new technetium complexes for eventual development of^99mTc radiopharmaceuticals. The feasibility of producing⁹⁶Tc (4.35 d) and^95mTc (61 d) was studied by the alpha bombardment of pure Nb targets (⁹³Nb-100%).⁹⁶Tc was obtained in a yield of 30 Ci/Ah using 16 MeV alphas, but it contained significant activity of⁹⁵Tc (20 h) Relatively pure⁹⁶Tc and^95mTc was produced in yields of 18 Ci/Ah and about 1 Ci/Ah respectively with alphas of suitable energy and after allowing for suitable cooling periods after the end of bombardment (EOB).     

Pyrethroids as household insecticides: analysis, indoor exposure and persistence

Summary Natural pyrethrins from insecticidal pyrethrum extract and pyrethroids (e.g. allethrin, tetramethrin, permethrin, cyphenothrin, cypermethrin, cyfluthrin) are active ingredients in insecticidal formulations such as powder, sprays, impregnated paper for electro-evaporators, mosquito coils, and solutions for wood treatment, all mainly intended for indoor use. Some commercial preparations contain also non-pyrethroid insecticides, such as dichlorovos, propoxur, or phoxim, and piperonyl butoxid as synergist. High-resolution gas-chromatography with oncolumn injection and FID and ECD detection is employed for the analysis of these insecticides in commercial formulations, in air during and after indoor application, and as residues on surfaces. The total input of pyrethroids into a large room amounts to 1 to 30 mg. The concentrations of the pyrethrins and pyrethroids in air (2 to 300 g/m³) and their deposition on surfaces (up to 1000 g/m²) reveal possible exposure of humans by inhalation (e.g. 30 g allethrin or 60 g tetramethrin) or by skin resorption (e.g. 200 g allethrin and up to 1000 g tetramethrin). The insecticides deposited on surfaces and some readily formed transformation products persist for 60 h or longer.Partly presented at the 7th International Congress of Pesticide Chemistry in Hamburg, August 5–10, 1990     

Gas-chromatographische Bestimmung von Spuren von n-Butylzinnverbindungen (Tetra-, Tri-, Di-) in Luft

Zusammenfassung n-Butylzinnverbindungen (Tetra-, Tri-, Di-) wurden aus der angesaugten Luft an Chromosorb 102 adsorbiert, mit HCl-haltigem Diethylether desorbiert, falls nötig mit Methylmagnesiumchlorid umgesetzt und die methylierten Verbindungen gas-chromatographisch mit einem zinnspezifischen flammenphotometrischen Detektor bestimmt. Die mittlere Wiederfindungsrate (0,09–40 g) von Bis(tri-n-butylzinn)oxid (TBTO) betrug: 93,3%; Streubereich der Einzelwerte ± 9,3% (P=95%, N=11). Wird 1 m³ Luft angesaugt, lassen sich noch Konzentrationen an n-Butylzinnverbindungen (Tetra-, Tri-, Di-) von 0,05 g/m³ bestimmen.In einem mit einer TBTO-haltigen Dispersionsfarbe gestrichenen Raum wurde die Temperaturabhängigkeit der Tri-n-butylzinn-Konzentration in der Luft untersucht. Der Vergleich mit den Resultaten von Bestimmungen des Totalzinngehaltes läßt den Schluß zu, daß in der Luft nur Tri-n-butylzinnverbindungen vorlagen.

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GLC-determination of traces of n-butyltin compounds (tetra-, tri-, di-) in the air

Summary n-Butyltin compounds (tetra-, tri-, di-) have been adsorbed on Chromosorb 102 from the aspired air, desorbed with HCl-containing diethylether and, if necessary, converted to the corresponding methyl derivatives by reaction with methylmagnesium chloride. The derivatives were determined by GLC with a tin-specific flame photometric detector. The mean recovery (0.09–40 g) of bis(tri-n-butyltin)oxide (TBTO) was 93.3%; tolerance limit ±9.3% (P=95%, N=11). With an air sample of 1 m³ it is possible to measure n-butyltin compounds (tetra-, tri-, di-) in concentrations down to 0.05 g/m³.In a room coated with a TBTO-containing latex-based paint, the temperature dependence of the tri-n-butyltin concentration in the air has been studied. Comparison with results of total tin determinations allows the conclusion that the air contained only tri-n-butyltin compounds.

     

The determination of atmospheric concentrations of the active ingredients of pesticide formulations by high-performance liquid chromatography

Summary Methods of sampling atmospheres contaminated by pesticides in factory and agricultural environments, and subsequent analysis by HPLC, are discussed. Air sampling is carried out using porous polymer or filter collection media, usually a 100 dm³ air volume is suitable. Detection limits with ultra-violet detection are in the range 0.1 to 10 g m^–3.Presented at the 14th International Symposium on Chromatography London, September, 1982     

Methode zur Messung gasförmiger Bleialkylverbindungen in Außenluft

Zusammenfassung Eine Methode zur Messung gasförmiger Bleitetraalkyle in Außenluft wurde beschrieben. Die Anreicherung der Bleialkyle erfolgt durch eine Adsorptionstechnik bei Flüssigluft-Temperatur. Die Sammelanordnung besteht aus einem Vorfilter, einer Vorabscheidekühlfalle und einem Adsorptionsrohr. Die dort angereicherten Bleialkyle werden durch Erhitzen wieder freigesetzt und mit einem Atomabsorptionsspektrometer bestimmt. Bei einem Sammelvolumen von 200 l Luft ergibt sich eine Nachweisgrenze von 1 ng Pb pro m³ Luft. Die Vertrauensgrenzen der Konzentrationsangaben sind besser als 9,5%.Die gemessenen Konzentrationen der gasförmigen Bleialkyle in Außenluft schwanken zwischen 0,001 g Pb/m³ in den Mittelgebirgen in der Nähe von Frankfurt am Main und 0,2 g Pb/m³ an einer verkehrsreichen Straße der Innenstadt.

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Method for measurement of gaseous lead alkyl compounds in outside air

Summary A method for measurement of gaseous lead tetraalkyls in outside air was described. The lead alkyls were enriched by an adsorption technique at fluid air temperature. The collection arrangement consists of a prefilter, a preseparation cooling tract and an absorption tube. The lead alkyls accumulated there are released again by heating and determined with an atomic absorption spectrometer. With a collection volume of 200 l of air, there is a detection limit of 1 ng lead per m³ air. The confidence limits of the concentration data are better than 9.5%. The measured concentrations of the gaseous lead alkyls in outside air vary between 0.001 g Pb/m³ in the Mittelgebirge near Frankfurt/Main and 0.2 g Pb/m³ on a street heavy with traffic in the center of Frankfurt.

     

Analysis of organobromine compounds and HBr in motor car exhaust gases with a GC/microwave plasma system

Summary In this investigation an analytical procedure for the determination of different organobromine compounds in motor car exhaust gases is developed in order to obtain a total balance of these compounds in this type of exhaust gas. For this purpose, adsorption sampling on Tenax GC combined with thermal desorption and a fast cold trap injection into the GC column system is used. A special capillary cold trap/thermodesorption system for a fast injection within 1 s is developed. The chromatographically separated fractions are identified by their retention times and elementspecific detection with a microwave plasma detector. Methyl bromide, 1,2-dibromoethane, and vinyl bromide are analysed in exhaust gases in cases where the gasoline contains 1,2-dibromoethane as an additive (leaded gasoline). The analysed bromine contents, which correspond to these organobromine compounds, are in the range of 90–190 g/m³, 15–85 g/m³, and 5–20 g/m³, respectively. The portion of the organobromine compounds is 22–44% of the total bromine which is emitted by the exhaust gases. The other portion contains mainly inorganic particulate bromide, which can be separated by filters. The concentration of the organobromine compounds decreases with increasing motor temperature. After conversion into 2-bromocyclohexanol and after gas chromatographic separation HBr is detected to be 5.8 g bromine per m³ exhaust gas, which corresponds to approximately 1% of the total bromine emission. 1,2-Dichloroethane is analysed in the range of 5–35 g Cl/m³, whereas the concentration of tetraalkyl lead in the exhaust gases is less than the detection limit of 6.7 g Pb/m³. The average bromine/lead ratio found in the filterable portion of the exhaust gases is 0.30 (by weight); the same ratio calculated for total bromine emission including the organobromine compounds is 0.47. Compared with the bromine/ lead ratio in gasoline of 0.39 this means that at least 17% of the total lead in the gasoline is not directly emitted with the motor car exhaust gases.

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Analyse von bromorganischen Verbindungen und HBr in Autoabgasen mit einem GC/Mikrowellenplasma-System

     

Determination of organometallics in intra-oral air by LT-GC/ICP-MS

Low temperature gas chromatography (LT-GC) coupled on-line with inductively coupled plasma mass spectrometry (ICP-MS) has been used to identify volatile metal and metalloid compounds in human breath. After cryogenic sampling, the gas sample has been separated without any clean-up by increasing the temperature (–100 to +200° C). Simultaneous determination of 11 elements with ICP-MS was used for screening analysis. The detection limits of volatile compounds in intra-oral air are in the range of ng m^–3. Dimethyl selenium has been determined in each gas sample from six test persons in the range of 0.08 to 0.98 g m^–3.     

A routine method for the determination of the TVOC content in wallcoverings using headspace gas-chromatography

A method for the fast routine analysis of the total content of volatile organic compounds in wallcoverings and paper products was developed, using headspace gas-chromatography for quantification. 57 wallcoverings of different types were investigated. Typical components were toluene, methyl-ethyl ketone, methyl-iso-butyl ketone, n-butyl acetate and iso-butyl acetate, all compounds being used as industrial solvents. The TVOC concentrations are calculated in toluene-carbon equivalents and ranged from 0.31 g/g to 1789 g/g with an average value of 123.22 g/g and a median of 20.37 g/g. To obtain an estimation of VOC-concentrations in indoor air, 10 selected wallcoverings were also analyzed in a 1 m³ climate test chamber. A correlation between headspace data and chamber concentrations could not be observed, which might be a result of increased analytical uncertainties at low emission rates under chamber conditions.     

Separation of Monovalent and Divalent Cations on a Pure Silica Gel Column with Dilute Oxalic Acid Containing 18-Crown-6 as Mobile Phase

Summary Pure silica gel (Pia Seed 5S-60-SIL) has been investigated as a cation-exchange stationary phase for ion chromatography of common monovalent and divalent cations (Li⁺, Na⁺, NH₄⁺, K⁺, Mg²⁺, and Ca²⁺) with conductimetric detection; dilute oxalic acid (0.05 mm oxalic acid, pH 4.1, to 1 mm oxalic acid, pH 3.0) was used as mobile phase. The Pia Seed 5S-60-SIL silica gel acted as a cation-exchange stationary phase for these cations when 0.2 mm oxalic acid at pH 3.6 was used as the mobile phase. Excellent simultaneous separation and highly sensitive indirect conductimetric detection of these cations were achieved in 20 min on a 150 mm × 4.6 mm i.d. Pia Seed 5S-60-SIL silica gel column with 0.2 mm oxalic acid containing 4 mm 18-crown-6 (1,4,7,10,13,16-hexaoxacycloctadecane), pH 3.7, as mobile phase (detection limits (signal-to-noise ratio, 3, injection volume, 20 L), were 0.15 m for Li⁺, 0.16 m for Na⁺, 0.21 m for NH₄⁺, 1.0 m for K⁺, 0.17 m for Mg²⁺, and 0.25 m for Ca²⁺). The proposed IC–CD method was successfully applied to the separation and detection of major cations (Na⁺, NH₄⁺, K⁺, Mg²⁺, and Ca²⁺) in rain and river water samples.