Abstract: A photoionization detector comprising multiple ionization cells for detecting the presence of chemical compounds in multiple fluid samples. The photoionization detector uses a single source of ultraviolet (UV) radiation to emit high energy photons into at least two ionization cells. Each ionization cell comprises at least one fluid inlet and at least one fluid outlet. Independent samples of fluid can be introduced into each cell and exposed to the UV radiation such that any molecules with an ionization energy lower that the energy of the photons are ionized. Each ionization cell also comprises a set of at least two electrodes arranged to generate an electric field such that ionized molecules are attracted to the electrode at lower voltage potential resulting in an electrical current.

Abstract: An assembly of chromatograph components which operate at a uniform elevated or reduced temperature and perform the functions of sample injection, precolumn backflush, analytical column selection, detection in a reduced mass and volume, and with a reduced surface area for reduced power consumption in accordance with use in a portable gas chromatograph is disclosed. Parts of the assembly including a switching valve assembly, a column plate, a thermal cover and a detector block are thermally-linked and those parts of the assembly which contact the sample including the gas chromatograph columns are maintained at a controlled temperature using, for example, an efficient axial heater, a Peltier cooler or a heat pipe and temperature sensors, thereby increasing analytical confidence.

Abstract: A fluid control valve arrangement allowing very complex valve interconnection schemes to be implemented in a small volume is disclosed. The fluid control valve arrangement utilizes seat plates positioned above and below a block to allow creation of three layers of material between valve elements on opposite sides of the block. Since there are three layers of material between blister valve elements on opposite sides of the block, there are two interfaces on separate levels from those levels contacting valve membranes and blister recesses upon which to form interconnection channels. Because each side of the block has one layer allocated for blisters and another allocated for formation of interconnection channels, very complex valve interconnection schemes may be implemented in a small volume.