Thomas Adam

Online characterization of regulated and unregulated gaseous and particulate exhaust emissions from two-stroke mopeds: a chemometric approach.

Two-stroke mopeds are a popular and convenient mean of transport in particular in the highly populated cities. These vehicles can emit potentially toxic gaseous and aerosol pollutants due to their engine technology. The legislative measurements of moped emissions are based on offline methods; however, the online characterization of gas and particulate phases offers great possibilities to understand aerosol formation mechanism and to adapt future emission standards. The purpose of this work was to study the emission behavior of two mopeds complying with different European emission standards (EURO-1 and EURO-2). A sophisticated set of online analyzers was applied to simultaneously monitor the gas phase and particulate phase of exhaust on a real time basis. The gaseous emission was analyzed with a high resolution Fourier transform infrared spectrometer (FTIR; nitrogen species) and a resonance-enhanced multiphoton ionization time-of-flight mass spectrometer (REMPI-ToF-MS; polycyclic aromatic hydrocarbons: PAH), whereas the particulate phase was chemically characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS; organic, nitrate and chloride aerosol) and a multiangle absorption photometer (MAAP; black carbon). The physical characterization of the aerosol was carried out with a condensation particle counter (CPC; particle number concentration) and a fast mobility particle sizer (FMPS; size distribution in real time). In order to extract underlying correlation between gas and solid emissions, principal component analysis was applied to the comprehensive online dataset. Multivariate analysis highlighted the considerable effect of the exhaust temperature on the particles and heavy PAH emissions. The results showed that the after-treatment used to comply with the latest EURO-2 emission standard may be responsible for the production of more potentially harmful particles compared to the EURO-1 moped emissions.

Resonance-Enhanced Multiphoton Ionization Time-of-Flight Mass Spectrometry for Detection of Nitrogen Containing Aliphatic and Aromatic Compounds: Resonance-Enhanced Multiphoton Ionization Spectroscopic Investigation and On-Line Analytical Application

Resonance-enhanced multiphoton ionization (REMPI) combined with time-of-flight mass spectrometry (TOFMS) is an analytical method capable of on-line monitoring of trace compounds in complex matrices. A necessary prerequisite for substance selective detection is spectroscopic investigation of the target molecules. Several organic nitrogen compounds comprising aliphatic and aromatic amines, nitrogen heterocyclic compounds, and aromatic nitriles are spectroscopically investigated with a tunable narrow bandwidth optical parametric oscillator (OPO) laser system providing a scannable wavelength range between 220 and 340 nm. These species are known as possible precursors in fuel–NO formation from combustion of solid fuels such as biomass and waste. A newly conceived double inlet system was used in this study, which allows rapid change between effusive and supersonic molecular beams. The resulting REMPI spectra of the compounds are discussed with respect to electronic transitions that could be utilized for a selective ionization of these compounds in complex mixtures such as combustion and process gases. The practicability of this approach is demonstrated by wavelength selected on-line REMPI-TOFMS detection of aniline and cyanonaphthalene in the burning chamber of a waste incineration plant. REMPI mass spectra recorded at different excitation wavelengths as well as variations in time show the utilization of species-selective REMPI-TOFMS detection for on-line monitoring of crucial substances in pollutant formation.

Application of modern online instrumentation for chemical analysis of gas and particulate phases of exhaust at the European Commission heavy-duty vehicle emission laboratory.

The European Commission recently established a novel test facility for heavy-duty vehicles to enhance more sustainable transport. The facility enables the study of energy efficiency of various fuels/scenarios as well as the chemical composition of evolved exhaust emissions. Sophisticated instrumentation for real-time analysis of the gas and particulate phases of exhaust has been implemented. Thereby, gas-phase characterization was carried out by a Fourier transform infrared spectrometer (FT-IR; carbonyls, nitrogen-containing species, small hydrocarbons) and a resonance-enhanced multiphoton ionization time-of-flight mass spectrometer (REMPI-TOFMS; monocyclic and polycyclic aromatic hydrocarbons). For analysis of the particulate phase, a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS; organic matter, chloride, nitrate), a condensation particle counter (CPC; particle number), and a multiangle absorption photometer (MAAP; black carbon) were applied. In this paper, the first application of the new facility in combination with the described instruments is presented, whereby a medium-size truck was investigated by applying different driving cycles. The goal was simultaneous chemical characterization of a great variety of gaseous compounds and particulate matter in exhaust on a real-time basis. The time-resolved data allowed new approaches to view the results; for example, emission factors were normalized to time-resolved consumption of fuel and were related to emission factors evolved during high speeds. Compounds could be identified that followed the fuel consumption, others showed very different behavior. In particular, engine cold start, engine ignition (unburned fuel), and high-speed events resulted in unique emission patterns.

Chemical characterization of emissions from modern two-stroke mopeds complying with legislative regulation in Europe (EURO-2).

In view of a new amendment to the European legislative regulation on emissions from two-stroke mopeds a study was carried out to comprehensively characterize exhaust gases of mopeds complying current EURO-2 emission standards. Three mopeds with different engine types (carburetor, direct injection, and electronic carburetion system ECS) where investigated by applying two different driving cycles, the legislative cycle ECE47 and the worldwide motorcycle test cycle WMTC. Thereby, particulate matter (PM), regulated compounds, carbonyls, volatile hydrocarbons (VOC), and particle-associated polyaromatic hydrocarbons (PAH) were analyzed and ozone formation potentials (OFP) as well as toxicity equivalents (TEQ) determined. The ECE47 emission factors for almost all species and moped types were much higher in the nonregulated, prior cold phase than in the hot phase, which is considered for legislation. Great differences for the mopeds could be observed for NO(x), VOC, and PM, whereas discrepancies between the driving cycles ECE47 and WMTC were smaller. In addition, a positive influence on exhaust composition caused by technical modifications of the ECS engine was determined. Results indicate that regulation of total hydrocarbons (THC) alone might not be sufficient to regulate PM, especially for direct injection engines. Moreover, recommendations for a revised future test protocol are demonstrated and discussed, whereby the cold phase and the hot phase are taken into account.

Real-time analysis of aromatics in combustion engine exhaust by resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS): a robust tool for chassis dynamometer testing

Resonance-enhanced multiphoton ionisation time-of-flight mass spectrometry (REMPI-TOF-MS) is a robust method for real-time analysis of monocyclic and polycyclic aromatic hydrocarbons in complex emissions. A mobile system has been developed which enables direct analysis on site. In this paper, we utilize a multicomponent calibration scheme based on the analytes’ photo-ionisation cross-sections relative to a calibrated species. This allows semi-quantification of a great number of components by only calibrating one compound of choice, here toluene. The cross-sections were determined by injecting nebulised solutions of aromatic compounds into the TOF-MS ion source with the help of a HPLC pump. Then, REMPI-TOF-MS was implemented at various chassis dynamometers and test cells and the exhaust of the following vehicles and engines investigated: a compression ignition light-duty (LD) passenger car, a compression ignition LD van, two spark ignition LD passenger cars, 2 two-stroke mopeds, and a two-stroke engine of a string gas trimmer. The quantitative time profiles of benzene are shown. The results indicate that two-stroke engines are a significant source for toxic and cancerogenic compounds. Air pollution and health effects caused by gardening equipment might still be underestimated.

Investigation of Tobacco Pyrolysis Gases and Puff-by-puff Resolved Cigarette Smoke by Single Photon Ionisation (SPI) - Time-of-flight Mass Spectrometry (TOFMS)

Abstract The work presented deals with the application of Single Photon Ionisation- Time-of-Flight Mass Spectrometry (SPI-TOFMS) for the investigation of tobacco smoke. SPI-TOFMS is a modern analytical technique, which enables the simultaneous analysis of a large number of organic species in complex gas mixtures in real time. The paper is a summary of a PhD thesis (1) and seven research articles, which were recently published in various scientific journals (2-8). Consequently, more detailed information on particular aspects can be found in there. The experimental part covers two different approaches, and therefore, it is divided into two sub-sections. In the first one, the SPI-TOFMS is coupled to a pyrolysis furnace. The objective is to examine the thermal behaviour of tobacco under various controlled conditions. In so doing, three tobacco types (Virginia, Oriental, and Burley) were pyrolysed in two reaction gas compositions (nitrogen and synthetic air) and seven different furnace temperatures (400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, and 1000 °C). Results can help to unravel the complex formation and decomposition reactions taking place when tobacco is heated. In the second part the SPI-TOFMS is connected to a cigarette smoking machine in order to investigate the behaviour of cigarette smoke constituents on a puff-by-puff basis. The work incorporates the comparison of whole smoke and gas phase of cigarette smoke, a puff-resolved quantification of several hazardous smoke constituents, and the overall chemical characterisation of the individual smoking puffs. In addition, a critical consideration of the prevailing smoking procedure is given when applied to single puff analysis. A further study examines the influence of five different cigarette lighting devices (gas lighter, electric lighter, candle, match, and burning zone of another cigarette) on the chemical composition of the first puff.

Simultaneous on-line size and chemical analysis of gas phase and particulate phase of mainstream tobacco smoke

Tobacco smoke is a complex and dynamic physical and chemical matrix in which about 4800 components have been identified. It is known that deposition efficiencies of smoke particles in the lung in the lung (60-80%) are greater than expected for smoke particles of 150-- 250 nm count median diameter (CMD). Various mechanisms have been put forward to explain this enhanced deposition pattern, including coagulation, hygroscopic growth, condensation and evaporation, changes in composition, or changes in inhalation behaviour. This paper represents one of three studies seeking to better quantify smoke chemistry, inhalation behaviour and cumulative particle growth. This information will improve dosimetry estimates in quantitative risk assessment tools as part of a harm reduction process. In this study smoke particle size and chemistry were measured simultaneously in real-time using electrical mobility spectrometry and soft-ionisation, time-of-flight mass spectrometry respectively. Qualitative puff-by-puff resolved yields of three selected compounds (acetaldehyde, phenol, and styrene) are shown and compared with particle number and count median diameter from different smoking intensities and filter ventilation. Yields of chemical analysis, particle diameter and concentration are in good agreement with the intensity of the smoking regime and the dilution of smoke by filter ventilation.

Photo-ionization mass spectrometry for on-line analysis of organic compounds in human breath and in tobacco smoke upon inhalation

Soft photo ionization mass spectrometry was applied successfully for on-line characterization of organic compounds in tobacco smoke during the smoking process (including mouth space measurements) and in the exhaled breath.