Henk L. C. Meuzelaar

Characterization of Fine Particulate Matter Produced by Combustion of Residual Fuel Oil

ABSTRACT Combustion experiments were carried out on four different residual fuel oils in a 732-kW boiler. PM emission samples were separated aerodynamically by a cyclone into fractions that were nominally less than and greater than 2.5 |j.m in diameter. However, examination of several of the samples by computer-controlled scanning electron microscopy (CCSEM) revealed that part of the PM2.5 fraction consists of carbonaceous cenospheres and vesicular particles that range up to 10 |j.m in diameter. X-ray absorption fine structure (XAFS) spectroscopy data were obtained at the S, V, Ni, Fe, Cu, Zn, and As K-edges and at the Pb L-edge. Deconvolution of the X-ray absorption near edge structure (XANES) region of the S spectra established that the dominant molecular forms of S present were sulfate (26-84% of total S) and thiophene (13-39% of total S). Sulfate was greater in the PM2.5 samples than in the PM25+ samples. Inorganic sulfides and elemental sulfur were present in lower percentages. The Ni XANES spectra from all of the samples agreed fairly well with that of NiSO4, while most of the V spectra closely resembled that of vanadyl sulfate (VO•SO4•xH2O). The other metals investigated (i.e., Fe, Cu, Zn, and Pb) also were present predominantly as sulfates. Arsenic was present as an arsen-ate (As+5). X-ray diffraction patterns of the PM2.5 fraction exhibit sharp lines due to sulfate compounds (Zn, V, Ni, Ca, etc.) superimposed on broad peaks due to amorphous carbons. All of the samples contain a significant organic component, with the loss on ignition (LOI) ranging from 64 to 87% for the PM2.5 fraction and from 88 to 97% for the PM2.5+ fraction. Based on 13C nuclear magnetic resonance (NMR) analysis, the carbon is predominantly condensed in graphitic structures. Aliphatic structure was detected in only one of seven samples examined.

Detection of the picolinic acid biomarker in Bacillus spores using a potentially field‐portable pyrolysis—gas chromatography—ion mobility spectrometry system

The absence of a field-portable device to provide real-time detection of Gram-positive bacterial spores has prompted the interfacing of a pyrolysis (Py) module to an existing, hand-held gas-chromatography—ion-mobility spectrometry (GC/IMS) device. In this configuration, spore detection is achieved by the observation of picolinic (2-pyridinecarboxylic) acid (PA), which is the most characteristic pyrolysis decomposition product of the parent dipicolinic (2,6-pyridinedicarboxylic) acid (DPA). Positive identification of PA was demonstrated using a laboratory-based GC instrument with dual, parallel mass spectrometry (MS) and IMS detectors. Spores and vegetative microorganisms of the genus Bacillus were characterized by the presence and absence of DPA, respectively, and the picolinic acid marker was identified from the GC/IMS and GC/MS profiles. A field-portable prototype Py-GC/IMS system is described and appears to provide similar bioanalytical information with respect to the laboratory-based system. Preliminary results of this study indicate that the degree of compound separation afforded by a short GC capillary column guards against common environmental interferences including urban particulate matter and biological particles such as fungal spores and pollen.

A flash pyrolysis and petrographic study of cutinite from the Indiana paper coal

Abstract Samples obtained from the high-volatile bituminous Indiana cuticle-rich and paper coals (Indiana U.S.A.) were investigated by white light and blue light microscopy and by Curie point pyrolysis-mass spectrometry in combination with multivariate data analysis, Curie point pyrolysis-gas chromatography and Curie point pyrolysis-gas chromatographymass spectrometry. Samples obtained from several sites and of different degrees of weathering were analyzed. The macerai cutinite from the same samples was studied as well. The cutinite was concentrated by a standard palynological chemical oxidation technique as well as by density gradient centrifugation. The major constituent of the Indiana paper coal samples appeared to be a recently discovered non-saponifiable polymethylenic biopolymer, present in both recent and fossil plant cuticles. The maceral cutinite is almost exclusively made up of this highly resistant biopolymer. It is shown that upon severe natural weathering this biopolymer, because of its resistance against organic alteration and diagenesis, is relatively enriched and manifests itself in humic coals as the maceral cutinite.

Factor analysis of the influence of changes in experimental conditions in pyrolysis—mass spectrometry

Abstract The qualitative changes in pyrolysis mass spectra obtained under various experimental conditions were studied by factor analysis. The parameters involved are the pyrolysis method (oven vs. filament), the method of cleaning the pyrolysis wire, the choice of the suspending liquid, the sample size, the filament position, the temperature-time profile and the temperature of the expansion chamber. For a number of these parameters, factor analysis of the data enabled a physico-chemical interpretation of the variations in the pyrolysis mass spectra to be made. An increased formation of dehydrogenated fragments was observed at higher equilibrium temperatures and for oven pyrolysis. Condensation of less volatile pyrolysis products at relatively cold parts of the inlet system (reaction tube and expansion chamber) was clearly observed.

Characterization and classification of Rocky Mountain coals by Curie-point pyrolysis mass spectrometry

A set of 102 coal samples from the Rocky Mountain coal province, selected from the Penn State Coal Sample Bank, was analysed by Curie-point pyrolysis mass spectrometry in combination with computerized pattern recognition techniques. The spectra obtained were shown to be quite representative for the coal seams with characteristic differences often present between different seams, fields or regions within the Rocky Mountain Coal province. In general, the spectra were found to be dominated by homologous ion series, e.g., representing dihydroxybenzenes, phenols, naphthalenes, benzenes, alkenes, dienes, alkyl fragments and sulphur compounds with varying degrees of alkyl substitution. The relative abundances of dihydroxybenzenes and naphthalenes were shown to correlate closely with differences in rank, whereas those of phenols, aliphatic hydrocarbons and sulphur compounds appeared to correlate more closely with differences in depositional environment. Different spectra -dominated by aliphatic compound series -were obtained from several samples of a boghead coal (Cannel King seam). Moreover, spectra of two of these boghead coal samples, known to be severely weathered, showed markedly increased CO2+ and C6H6+ signals, indicating the presence of benzenecarboxylic acids. Factor analysis of pyrolysis m.s. data revealed the two main underlying chemical tendencies to be a shift from heteroatomic compounds to hydrocarbon series with increasing rank and a difference in degree of aromaticity corresponding primarily to differences in depositional environment. The dominant rank-related factor exhibited a clear coalification break between the ASTM hvC bituminous and hvB bituminous ranks and appears to represent a significant shift in coalification mechanisms. It was demonstrated that rank-dependent differences in the pyrolysis mass spectra enable correct classification of the spectra into four ASTM rank classes (subbituminous, hvC, hvB and hvA bituminous) in 90% of all cases. Moreover, the discovery of a marked aliphaticity/aromaticity factor in the data could be useful for the direct measurement of aromaticity (fa) from pyrolysis mass spectra of whole coals.

The effects of sample preparation, pyrolysis and pyrolyzate transfer conditions on pyrolysis mass spectra

Abstract Two different biopolymers, bovine serum albumin and glycogen, were examined by pyrolysis-mass spectrometry under various experimental conditions. The parameters tested include the method of cleaning the pyrolysis wire, the choice of the sample solvent, the sample size, the temperature-time profile and the temperature of the mass spectrometric inlet system. In order to determine quantitatively the effects of changes in experimental conditions on reproducibility of the spectra, the differences observed between the pyrolysis mass spectra represented as numerical dissimilarity values. It is concluded that the long-term differences observed are only partly explained by fluctuations in the conditions studied. However, it appears feasible to define a set of standard conditions with respect to the production of the pyrolyzate which should afford a reasonable degree of interlaboratory reproducibility.

Field‐portable, automated pyrolysis‐GC/IMS system for rapid biomarker detection in aerosols: A feasibility study

A prototype automated pyrolysis-gas chromatography/ion mobility spectrometry (Py-GC/IMS) instrument was developed for (bio)aerosol characterization. The system combines a commercially available, hand-held GC/IMS device with a specially built platinum wire grid heater, a 1-in.-diam. quartz microfiber filter and a 60-l/min air pump. The prototype Py-GC/IMS system can be operated in stand-alone mode or in series with a particle concentrator. Fully automated collection/desorption/pyrolysis of aerosols and other particulate matter can be performed at repetition rates of up to 60 h−1 by means of a special remote control and display software package. The feasibility of detecting submicrogram quantities of Bacillus endospores with the use of picolinic acid and pyridine as biochemical marker compounds for the characteristic dipicolinic acid moiety in spore cell walls was demonstrated by laboratory experiments as well as preliminary field tests. Other particulate matter that could be collected and analyzed includes allergens such as pollen or home dust, as well as a broad range of bioaerosols and reaerosolized organics like explosives or drugs. In addition to its potential use as a screening device for the presence of specific classes of aerosol components, the Py-GC/IMS system has been demonstrated to retain its capability to detect and identify a broad range of volatile and semivolatile organic compounds.

Production of diethyl carbonate from ethanol and carbon monoxide over a heterogeneous catalytic flow reactor

Abstract Diethyl carbonate (DEC) is a candidate for use as an oxygen-containing additive in gasoline and diesel fuel to diminish pollutant emissions. The synthesis of DEC by the oxidative carbonylation of ethanol in the gas phase over heterogeneous CuCl 2 /PdCl 2 catalysts supported on activated carbon (AC) has been investigated using a laboratory-scale continuous flow reactor with online GC/MS. Influences of various reaction conditions and catalyst pretreatment on the DEC yield and selectivity have been tested. Yield of DEC at 150 °C reached a maximum of 12.5 wt.% and was found to increase with an increase of residence time, reaction temperature, and reaction pressure as expected. The relationship between CO flow rate and production of DEC showed three distinct regions of DEC production. A by-product, diethoxymethane (DEM), was formed when ethanol was introduced in stoichiometric excess. Catalyst pretreated with KOH presented the best catalytic performance, and all metal hydroxides tested enhanced the yield of and selectivity for DEC simultaneously. However, the CuCl 2 /PdCl 2 /AC–KOH catalyst with a higher OH/Cu mole ratio than 2.0 showed an even lower DEC yield than that found using a CuCl 2 /PdCl 2 /AC catalyst without KOH.

Noise reduction of fast, repetitive GC/MS measurements using principal component analysis (PCA)

Principal component analysis (PCA) was applied to the noise reduction of low ppb level benzene, toluene, ethyl benzene, xylene (BTEX) type gas chromatography/mass spectrometry (GC/MS) measurements (i.e. BTEX) with a fast, repetitive GC/MS system. The first three principal components (PCs) accounting for approximately 60‐80% of the total variance in the original data could be attributed to chemical components, whilst the remaining PCs were found to be due to noise. Reconstruction of the data from the first three PCs resulted in noise reduction with improved signal fidelity. The results of PCA were comparable with those achieved by a Fourier transform method. ©1999 Elsevier Science B.V. All rights reserved.

Performance advances in ion mobility spectrometry through combination with high speed vapor sampling, preconcentration and separation techniques

Abstract Rugged, low weight, hand-held ion mobility spectrometry devices, initially developed for chemical warfare detection purposes, possess attractive characteristics as field-portable instruments for paramilitary (treaty verification, chemical demilitarization, drug interdiction, counterterrorism operations) and civilian (environmental monitoring, forensic characterization, process control) applications. Generally, however, such devices tend to exhibit limited resolution, narrow dynamic range, nonlinear response and long clearance times which severely limit their usefulness for qualitative and quantitative analysis of mixtures. To overcome these restrictions a prototype combined gas chromatography-ion mobility spectrometry (GC-IMS) unit was constructed by replacing the membrane inlet of a military IMS device known as the CAM (chemical agent monitor) with suitable front-end modules. These modules enable high speed automated vapor sampling (AVS), microvolume preconcentration/thermal desorption, and isothermal GC preseparation of analytes using a short capillary column while operating the IMS source and cell at subambient pressures as low as 0.5 atm. The AVS-GC-IMS methodology sharply reduces competitive ionization and facilitates identification of mixture components, thereby enabling quantitation of volatile and semivolatile compounds over a broad range of concentration in air. At higher concentration levels (e.g. > 1 ppm) using the AVS inlet in automatic attenuation control (AAC) mode maintains excellent linear response. At ultralow concentration levels, e.g.