Abstract: A method and device for determining the concentration of analytes in a sample. The device has a surface with an extraction coating thereon. The method is carried out while the sample is highly agitated to maintain a substantially constant boundary layer. The sample is brought into contact with the coating for a limited time so that all the analytes that pass through the boundary layer are adsorbed by the coating. The amount of analytes in the coating is determined and the concentration of those same analytes in the sample is then calculated from the diffusion coefficient of the analytes. The device is first calibrated using analytes of known concentration.

Abstract: A method and device for determining the concentration of analytes in a sample. The device has a surface with an extraction coating thereon. The method is carried out while the sample is highly agitated to maintain a substantially constant boundary layer. The sample is brought into contact with the coating for a limited time so that all the analytes that pass through the boundary layer are adsorbed by the coating. The amount of analytes in the coating is determined and the concentration of those same analytes in the sample is then calculated from the diffusion coefficient of the analytes. The device is first calibrated using analytes of known concentration.

Abstract: A device for carrying out solid phase microextraction is a fiber contained in a syringe. When it is desired to analyze a sample in a bottle having a septum, the needle is inserted through the septum and the plunger is depressed so that the fiber will extend into the sample. After one or two minutes, the plunger is moved to the withdrawn position so that the fiber will return to the needle and the syringe is withdrawn from the sample bottle. The syringe is then inserted through a septum in a gas injection port of a gas chromatograph. The plunger is again depressed so that the fiber will extend into the gas chromatograph and an analysis of the components on the fiber is carried out. Then, the plunger is moved to the withdrawn position and the syringe is withdrawn from the injection port.

Abstract: A device for carrying out solid phase microextraction is a fiber contained in a syringe. The fiber can be solid or hollow. The syringe has a barrel and a plunger slidable within the barrel, the plunger having a handle extending from one end of the barrel. A hollow needle extends from an end of the barrel opposite to the plunger. The fiber is contained in the needle. When the plunger is depressed, the fiber extends beyond a free end of the needle and when the plunger is in a withdrawn position, the fiber is located within the needle. The syringe protects the fiber from damage. When it is desired to analyze a sample in a bottle having a septum, the needle is inserted through the septum and the plunger is depressed so that the fiber will extend into the sample. After one or two minutes, the plunger is moved to the withdrawn position so that the fiber will return to the needle and the syringe is withdrawn from the sample bottle.

Abstract: A method and device for determining the concentration of analytes in a sample. The device has a surface with an extraction coating thereon. The method is carried out while the sample is highly agitated to maintain a substantially constant boundary layer. The sample is brought into contact with the coating for a limited time so that all the analytes that pass through the boundary layer are adsorbed by the coating. The amount of analytes in the coating is determined and the concentration of those same analytes in the sample is then calculated from the diffusion coefficient of the analytes. The device is first calibrated using analytes of known concentration.

Abstract: A hand-held syringe-like device has needle containing a trap with a barrel and plunger to draw air into and out of the needle through the trap. In a method of operating the device, particulate matter in air is retained in the trap and subsequently analytes from the trap are desorbed in an analytical instrument.

Abstract: A microchannel that can be used for separating two or more substances present in a sample has a first substrate and a second substrate with printed component printed on one or both of the substrates and is shaped to define a perimeter of the channel. The substrates are affixed to one another so that the component is sandwiched between the substrates and is in contact with both substrates. The microchannel is constructed using printing techniques to define the channel on one or both of the substrates.

Abstract: A hand-held syringe-like device has needle containing a trap with a barrel and plunger to draw air into and out of the needle through the trap. In a method of operating the device, particulate matter in air is retained in the trap and subsequently analytes from the trap are desorbed in an analytical instrument.

Abstract: A device for carrying out solid phase microextraction is a tubular member having one closed end and one open end with an extracting surface within said tubular member. The extracting surface can be an extracting phase coating extending over a zone within the tubular member. The tubular member has a heater that can be used for either or both drawing fluid carrier into the tubular member or assisting in desorbing analytes into an injector of an analysis instrument. The tubular member can also be mounted in a housing with an airtight cavity and a plunger. A method of operation of the device is also provided. Previously, samples were analyzed using liquid-liquid extraction or using cartridges. Both of these methods are relatively expensive and time consuming. Both of these methods also require the use of solvents which can be difficult and expensive to dispose of.

Abstract: An improved apparatus and method for the capillary electrophoretic separation of chemical compounds comprises carrying out on-line sample preparation by means of semipermeable membranes connected to the capillary separation column for selective introduction of ampholytes into the capillary separation column. Semipermeable membrane means may also be used on-line for preliminary desalting of the sample prior to its introduction into the separation column.

Abstract: The separations resulting from capillary electrophoresis performed in a microbore capillary tube are detected on-line by focusing a light beam in the form of a line or sheet of light on the capillary passage in which the separations take place so that the width of the sheet of light encompasses the length of the passage in which separations of interest are expected to take place. The separations form concentration gradients in the capillary passage encompassed by the light beam and cause refraction of portions of the light beam and variations in the intensity of the light beam due to such refraction. Alternately, the separated components may absorb light of certain frequencies so if the light beam includes light of the certain frequencies, variation in the intensity of the light beam is caused by such absorbance.

Abstract: A device and method for isoelectric focusing of ampholytes in a buffer uses a cone-shaped capillary with a positive electrode connected at a narrow end and a negative electrode connected at the wide end of the capillary. The electrical potential across the buffer creates a temperature gradient which, in turn, creates a pH gradient. The electric current also creates an electric field gradient which focuses the ampholytes. Previous devices and methods use carrier ampholytes or use temperature baths to create a temperature gradient.

Abstract: A device for carrying out solid phase microextraction is a fiber contained in a syringe. The fiber can be solid or hollow. The syringe has a barrel and a plunger slidable within the barrel, the plunger having a handle extending from one end of the barrel. A hollow needle extends from an end of the barrel opposite to the plunger. The fiber is contained in the needle. When the plunger is depressed, the fiber extends beyond a free end of the needle and when the plunger is in a withdrawn position, the fiber is located within the needle. The syringe protects the fiber from damage. When it is desired to analyze a sample in a bottle having a septum, the needle is inserted through the septum and the plunger is depressed so that the fiber will extend into the sample. After one or two minutes, the plunger is moved to the withdrawn position so that the fiber will return to the needle and the syringe is withdrawn from the sample bottle.

Abstract: A device and process for increasing analyte concentration in a sorbent from a source of analytes contained in a sample uses means for increasing a temperature differential between the sample and the sorbent. The sorbent can be a polymeric coating on a substrate. The sorbent is located in a headspace of the sample and has internal cooling means such as liquid carbon dioxide so that the sorbent can be cooled relative to the sample. Preferably, the sample is heated to further increase the temperature differential between the sample and the sorbent. As the temperature differential increases, a partition coefficient of the sorbent/sample also increases. Preferably, the sorbent is located in a headspace of the sample. Previously, for certain analytes, the partition coefficient was too low and the concentration of analytes extracted into the sorbent from the sample was insufficient to provide an accurate measurement of concentration.

Abstract: A process and a device for the continuous extraction and analysis of chemical substances from solute fluid using membrane is characterized by passing solute fluid 14 through housing 20 on one side of a semipermeable structure 19 and simultaneously passing extracting fluid 11 through the housing on the other side of the semipermeable membrane structure. Substances passing from solute fluid through the semipermeable membrane structure into the extracting fluid are delivered by the extracting fluid as carrier, into a sorbing phase 27. Cooling 28 and heating 24 of the sorbing phase allows substances to be concentrated and detected by detector 50 and to be continuously monitored. Extracting fluid may be a gas or a pressurized dense gas. Extraction using pressurized dense gas and membrane is achieved by maintaining the pressure of the solute fluid and the pressurized dense gas within a high pressure housing substantially equal.

Abstract: The separations resulting from capillary electrophoresis performed in a microbore capillary tube are detected on-line by focusing a light beam in the form of a line or sheet of light on the capillary passage in which the separations take place so that the width of the sheet of light encompasses the length of the passage in which separations of interest are expected to take place. The separations form concentration gradients in the capillary passage encompassed by the light beam and cause refraction of portions of the light beam. The variation in the intensity of light along the width of the light beam after passage through the sample is sensed and is indicative of the concentration gradients and separation occurring in the sample. An apparatus including a relatively short capillary tube with liquid reservoirs secured at each end may be used with the detector to perform various capillary electrophoretic separation techniques.

Abstract: The separations resulting from capillary electrophoresis performed in a microbore capillary tube are detected on-line by focusing a light beam in the form of a line or sheet of light on the capillary passage in which the separations take place so that the width of the sheet of light encompasses the length of the passage in which separations of interest are expected to take place. The separations form concentration gradients in the capillary passage encompassed by the light beam and cause refraction of portions of the light beam. The variation in the intensity of light along the width of the light beam after passage through the sample is sensed and is indicative of the concentration gradients and separation occurring in the sample. An apparatus including a relatively short capillary tube with liquid reservoirs secured at each end may be used with the detector to perform various capillary electrophoretic separation techniques.

Abstract: A method and apparatus for delivering supercritical fluids uses one or two high pressure vessels. Each vessel is cooled below the critical temperature of the fluid while the vessel is being filled. The inlet is then closed and the vessel is heated to attain a predetermined pressure. The outlet of the vessel is then opened and supercritical fluid flows from the vessel for use in various processes such as extraction or chromatography. As the fluid flows from the high pressure vessel, the pressure is controlled by adjusting the temperature of the high pressure vessel. Usually, the temperature of the vessel will be increased as the supercritical fluid exits from the vessel. When two high pressure vessels are used, the vessels can be refilled on an alternating basis so that a continuous supply of supercritical fluid can be made available as long as it is required. The high pressure vessels can be two pieces of stainless steel tubing.

Abstract: The sensitivity of refractive gradient detectors for detecting refractive index gradients in samples flowing through samples chambers is increased by detecting the gradients formed in the direction perpendicular to the direction of flow of the sample through the sample chamber and by detecting such gradients simultaneously intermediate the central axis and sides of the sample chamber on opposite sides of the central axis. A preferred detector uses two spaced, parallel probe light beams passing through the sample chamber between the central axis and sides of the chamber on opposite sides of the axis, with each beam preferably centered about half way between the axis and the respective side. A sensor detects relative movement of the probe beams caused by a refractive index gradient in the sample but preferably compensates for parallel movement of the parallel light beams caused by positional instability or mechanical movement of the light source.

Abstract: A differential, sequential detector, and method, for detecting refractive index gradients in a sample and for producing an output signal approximating a derivative of the refractive index gradient utilizes two closely spaced, parallel probe light beams passing through the sample with the beams separated along the direction of any expected gradient to be detected. A sensor is arranged to measure and produce an output signal proportional to the difference in movement of the two beams. The sensor is preferably arranged so that only complementing portions of each beam will fall on the sensing area of the sensor so that parallel movement of the beams will change equally the respective complementary portions sensed to maintain a constant output from the sensor, but movement of one beam relative to the other beam will produce a change in the sensor output proportional to the relative movement and approximating the derivative of refractive index gradient causing the relative beam movement.