Five nonaqueous solvents (acetonitrile, methanol, N,N-dimethylformamide, dimethyl sulfoxide, formamide) and deionized water were investigated for their ability to support electroosmotic flow (EOF) without electrolytic additives. In general, flow was found to be equal to or greater than flow with typical CE buffer systems. The magnitude of EOF was determined for each solvent by open tubular capillary electrophoresis (CE) and related to viscosity (eta), dielectric constant (epsilon), and the ratio of dielectric constant to viscosity (eta/epsilon). Zeta potentials (zeta) were derived indirectly from flow data and tabulated. Comparisons of flow behavior and zeta were made between pure solvents and conventional CE buffers, and questions of equilibrium and reproducibility were addressed. Similar experiments were performed using hydroorganic mobile phases (ACN/water, MeOH/water) across the complete compositional range (100% water-100% organic), with flow characteristics and zeta reported for each mobile phase system. Packed capillary columns (5-microns ODS) were evaluated for flow and retention stability under capillary electrochromatographic (CEC) conditions. A separation of 11 polycyclic aromatic hydrocarbons was performed in under 13 min by CEC with an ACN/water mobile phase. Reduced plate heights (h) were calculated between 2.5 and 3.0 for solutes with capacity factors (k') up to 4.5 for the most retained solute.

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High-speed tomographic imaging of hostile engineering processes using absorptionbased measurements presents a number of difficulties. In some cases, these challenges include severe limitations on the number of available measurement paths through the subject, and the process of designing the geometrical arrangement of those paths for best imaging performance. This paper considers the case of a chemical species tomography system based on near-IR spectroscopic absorption measurements, intended for application to one cylinder of a multicylinder production engine. Some of the results, however, are applicable also to other hardfield tomographic modalities in applications where similar constraints may be encountered. A hitherto unreported design criterion is presented for optimal beam geometry for imaging performance, resulting in an irregular array with only 27 measurement paths through the subject for the engine application. Image reconstruction for this severely limited geometry is considered at length, using both simulated and experimental phantom data. Novel methods are presented for the practical generation of gaseous phantoms for calibration and testing of the system. The propane absorption coefficient at 1700nm is measured. Quantitative imaging of propane plumes in air is demonstrated, showing good localisation of circular plumes with diameter as small as 1/5 of the subject diameter and excellent imaging of multiple plumes.

Design requirements for an 8000 frame/s dual-wavelength ratiometric chemical species tomography system, intended for hydrocarbon vapor imaging in one cylinder of a standard automobile engine, are examined. The design process is guided by spectroscopic measurements on iso-octane and by comprehensive results from laboratory phantoms and research engines, including results on temporal resolution performance. Novel image reconstruction techniques, necessary for this application, are presented. Recent progress toward implementation, including details of the optical access arrangement employed and signal-to-noise issues, is described. We present first cross-cylinder IR absorption measurements from a reduced channel-count (nontomographic) system and discuss the prospects for imaging.

This paper reports the application of optical tomography and Chemical Species Tomography (CST) to the characterisation of the in-cylinder

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