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.
Application of exchangers with crown ethers as anchor groups in analytical and preparative chemistry
Abstract Exchangers with cyclic polyethers as anchor groups have been prepared by condensation, substitution and polymerizatin reactions. The exchangers show high resistance to chemicals, temperature and radiolysis. The selectivity for different salts depends on the catio, anion, solvent and size of the ring, and also on the type and basicity of the hetero atom (O, N, S). The exchangers have wide application in analytical chemisgtry, such as in separations of cations with a common anion ( e.g. , alkaline and alkaline earth metals, heavy and precious metals), anions with a common cation ( e.g. , halides and pseudohalides) and organic compounds, trace enrichment ( e.g. , radionuclides) and the determination of water. The preparative applications of the exchangers include salt conversions and the activation of anions for organic syntheses. A number of reaction can be carried out or improved in anhydrous solutions with the help of the exchangers. They can easily be recovered by filtration and solvent is not contaminated.