A gas chromatography-quartz crystal microbalance for speciation of sulfur compounds in landfill gas.
A new method, based on separation with gas chromatography and detection with a quartz crystal microbalance, was used for the quantification of ethane-1-thiol, propane-1-thiol, ethyl methyl sulfide, propane-2-thiol, butane-2-thiol and butane-1-thiol. The analytical error, the analysis time and the general analytical performance are identical for gas chromatography-mass spectrometry (GC-MS) and gas chromatography-quartz crystal microbalance (GC-QCM). However, the GC-QCM method constitutes a low cost alternative to GC-MS for monitoring individual sulfur compounds in landfill gas. It is an easily assembled apparatus made with an injection device, a furnace, a column, a crystal cell and a quartz crystal.
The development of sampling and gas chromatography-mass spectrometry analytical procedures to identify and determine the minor organic components of landfill gas.
Modified drive-in piezometers provided quick and inexpensive probes to give access to the undiluted landfill gas below ground level. Samples collected on Tenax GC and Porapak Q adsorption tubes were thermally desorbed and injected into a gas Chromatograph through a cold trap. Aqueous condensate samples were injected directly by syringe. Chromosorb 101, Tenax GC and Triton X100/KOH packed columns, and an SE30 capillary column were used, together with full-scan and selective-ion mass spectrometry. Limits of detection, all less than 1 mg m (3), and calibration correlation coefficients were determined for the least tractable components, i.e., free acids, amines and alcohols. A detection limit of 0.1 mg m (3), based on anisole as internal standard, was estimated for all other compounds. The standard deviation for the whole procedure, with full-scan mass spectrometry, was +/-55% of the mean. A large part of this was due to an instrumental error, standard deviation = 33% of the mean, that was inherent in the manual operation of the mass-spectrum chart-recorder. These procedural errors were insignificant in comparison with the variations caused by the type of site and the age of the fill.
Identification of Dihydroxy Aromatic Compounds in a Low-Temperature Pyrolysis Coal Tar by Gas Chromatography−Mass Spectrometry (GC−MS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)
Dihydroxy aromatics in coal tar undergo rapid coupling reactions with each other and with some coal-derived species during coal pyrolysis and liquefaction. However, only limited information on the structure of dihydroxy aromatics is known. In this study, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography−mass spectrometry (GC−MS) were used to characterize the dihydroxy aromatics in a low-temperature pyrolyzed coal tar and its distillate and residue fractions. Negative-ion electrospray ionization (ESI) FT-ICR MS spectra of coal-tar-derived samples had low molecular masses and narrow mass ranges. Negative-ion ESI is extremely selective for the dihydroxy aromatics present in coal tar. The O2 class species had the highest ion intensity among the species in the negative-ion FT-ICR mass spectrum for each sample. Dihydroxy compounds with an aromatic core structure of benzene, indan, biphenyl (and/or acenaphthene), and naphthalene were identified in the distillate fract...