Abstract: A fluid flow control valve comprises (a) a high pressure region adapted to contain a fluid at its supercritical or nearcritical temperature and pressure conditions and connected via an orifice to a low pressure region, (b) a seat adjacent the orifice, (c) a sealing element positionable against the seat to form a seal between the high pressure region and the low pressure region, and (d) an electrically and/or electronically controlled actuator operable to move the sealing element against and/or away from the seat to allow control of fluid flow from the high pressure region to the low pressure region. In a specific embodiment, the high pressure region contains a fluid at its supercritical or nearcritical temperature and pressure conditions. The valve may be used, for example, to provide very low flow rates, for example, for supercritical fluid chromatography, supercritical fluid extraction, critical point drying, supercritical fluid cleaning, and supercritical fluid separation methods.

Abstract: A fluid flow control valve comprises (a) a high pressure region adapted to contain a fluid at its supercritical or nearcritical temperature and pressure conditions and connected via an orifice to a low pressure region, (b) a seat adjacent the orifice, (c) a sealing element positionable against the seat to form a seal between the high pressure region and the low pressure region, and (d) an electrically and/or electronically controlled actuator operable to move the sealing element against and/or away from the seat to allow control of fluid flow from the high pressure region to the low pressure region. In a specific embodiment, the high pressure region contains a fluid at its supercritical or nearcritical temperature and pressure conditions. The valve may be used, for example, to provide very low flow rates, for example, for supercritical fluid chromatography, supercritical fluid extraction, critical point drying, supercritical fluid cleaning, and supercritical fluid separation methods.

Abstract: A method for producing a biodiesel fuel product from biological material is disclosed which comprises extracting lipids from the biological material with a pure or alcohol-modified supercritical fluid in an extractor, passing the extract directly into a reactor wherein a transesterification reaction is induced between the extracted lipids and alcohol with additional alcohol added if needed, forming glycerol and fatty acid alkyl esters, passing the mixture into one or more separators to remove the glycerol and fatty acid alkyl ester products, removing wastes, and recycling the critical fluid solvent and unreacted alcohol to the extractor. An improvement to biodiesel preparation is afforded by the simplification of the extraction and reaction processes into a single flowing system. According to the invention, a biodiesel fatty acid alkyl ester product can be prepared directly from biological material feedstock, such as oil-containing seeds, without the need for prior isolation of the oil.

Abstract: Methods for determining the amount of volatile electrolyte present in an aqueous liquid sample comprise transferring the electrolyte from the aqueous liquid sample to an absorber solution across a gas-permeable membrane which is non-passable to the aqueous liquid sample and measuring the change in electrical conductivity of the absorber solution during the transfer period. The absorber solution contains a solute which enhances the transfer of the electrolyte. Apparatus for conducting such methods include an absorber solution containing a solute which enhances the transfer of the electrolyte.

Abstract: Methods and apparatus for delivering physiologically active compounds to a target human or animal employ a supercritical fluid solution comprising a supercritical fluid solvent and a physiologically active solute. The supercritical fluid solution is passed into a subcritical region to evaporate the solvent and form a gas-borne dispersion of solute particles. The gas-borne dispersion of solute particles is administered directly to the target human or animal. The apparatus for delivering the physiologically active compound are of the hand-held type.

Abstract: A method for depositing a film of a desired material on a substrate comprises dissolving at least one reagent in a supercritical fluid comprising at least one solvent. Either the reagent is capable of reacting with or is a precursor of a compound capable of reacting with the solvent to form the desired product, or at least one additional reagent is included in the supercritical solution and is capable of reacting with or is a precursor of a compound capable of reacting with the first reagent or with a compound derived from the first reagent to form the desired material. The supercritical solution is expanded to produce a vapor or aerosol and a chemical reaction is induced in the vapor or aerosol so that a film of the desired material resulting from the chemical reaction is deposited on the substrate surface. In an alternate embodiment, the supercritical solution containing at least one reagent is expanded to produce a vapor or aerosol which is then mixed with a gas containing at least one additional reagent.