Abstract: A method and apparatus for detecting mercury in air includes passing a substantial quantity of air through a concentrator column containing gold film whereby a gold-mercury amalgam is formed, purging the concentrator column with nitrogen gas for a predefined period of time to remove oxygen and other organics from the concentrator column, quickly heating the concentrator column to a substantial temperature to decompose the gold-mercury amalgam forming mercury gas, and injecting the mercury gas into a photoionization detector system. The apparatus includes a quartz housing having a quartz body defining an internal volume, a gas inlet, a gas outlet, and a heater end, and a concentrator element sealingly disposed within the quartz housing, the concentrator element having a first element portion and a second element portion, a film of gold deposited on at least a first element portion disposed in the quartz body.

Abstract: A method and apparatus for detecting mercury in air includes passing a substantial quantity of air through a concentrator column containing gold film whereby a gold-mercury amalgam is formed, purging the concentrator column with nitrogen gas for a predefined period of time to remove oxygen and other organics from the concentrator column, quickly heating the concentrator column to a substantial temperature to decompose the gold-mercury amalgam forming mercury gas, and injecting the mercury gas into a photoionization detector system. The apparatus includes a quartz housing having a quartz body defining an internal volume, a gas inlet, a gas outlet, and a heater end, and a concentrator element sealingly disposed within the quartz housing, the concentrator element having a first element portion and a second element portion, a film of gold deposited on at least a first element portion disposed in the quartz body.

Abstract: A method for detecting a chemical species includes providing in a vessel an acidic sample containing an ionic chemical species to be measured where a substrate of the species to be formed is ionizable by radiant energy provided by a photoionization detector in detector system and a headspace above the acidic sample, adding a preselected reducing agent to the aqueous sample and forming an ionizable chemical gas species in the aqueous sample where the ionizable chemical gas species evolves out of the aqueous sample and into the headspace forming a gas sample, moving the gas sample containing the ionizable chemical gas species from the headspace of the vessel out of the vessel and through a precolumn, and moving the gas sample containing the ionizable chemical gas species from the precolumn into one of (1) a detector system or (2) an oxygen-retaining column before the detector system.

Abstract: A method for detecting a chemical species includes providing in a vessel an acidic sample containing an ionic chemical species to be measured where a substrate of the species to be formed is ionizable by radiant energy provided by a photoionization detector in detector system and a headspace above the acidic sample, adding a preselected reducing agent to the aqueous sample and forming an ionizable chemical gas species in the aqueous sample where the ionizable chemical gas species evolves out of the aqueous sample and into the headspace forming a gas sample, moving the gas sample containing the ionizable chemical gas species from the headspace of the vessel out of the vessel and through a precolumn, and moving the gas sample containing the ionizable chemical gas species from the precolumn into one of (1) a detector system or (2) an oxygen-retaining column before the detector system.

Abstract: A method for determining nitrogen oxides in gaseous or liquid samples is disclosed. A semi-permeable membrane- type sensor comprising a sensor electrode, reference electrode and an electrolyte having a pH range of 6.8-8.0 or 8.0-9.2 is used. Potential between the electrodes is monitored as a measure of nitrogen oxides in the sample. When an electrolyte having a pH range of 8.0-9.2 is used the electrolyte additionally contains at least 25% v/v of a water miscible solvent having a dielectric constant of at least 10.

Abstract: A method is disclosed for determining carbon dioxide content in gaseous or liquid samples. A semi-permeable membrane-type sensor comprising a sensor electrode, reference electrode and an electrolyte having a pH range of 9.5-11.0 or 10.7-12.0 is used. Potential between the electrodes is monitored as a measure of carbon dioxide in the sample. When an electrolyte having a pH range of 10.7-12.0 is used the electrolyte additionally contains at least 255 v/v of a water miscible solvent having dielectric constant of a least 10.

Abstract: A method of determining ammonia in a gaseous or liquid sample is disclosed. A sensor comprising a sensing electrode, a reference electrode, a semi-permeable membrane and an electrolyte is used. The electrolyte is buffered to a pH value between 4.5 and 6.5 and is initially free of any salt capable of dissociating to form therein ammonium ion. The electrolyte may optionally contain at least 25% v/v of a water miscible solvent having a dielectric constant of at least 10. In the latter case the pH of the electrolyte is between 5.5 and 7.5. The potential between the sensing electrode and reference electrode is monitored as a measure of ammonia in the sample.

Abstract: A gas discharge lamp for emitting vacuum UV radiation, comprising a lamp body filled at low pressure with a gas capable of emitting radiation in the vacuum UV range (e.g., argon), electrodes within the lamp body for passing an electric field across the gas, a crystalline window (e.g., lithium fluoride) in the body for transmitting the vacuum UV radiation emitted by the gas, wherein the crystalline window is constructed of a material that, when exposed to the vacuum UV radiation emitted by the gas, forms color centers that block transmission of the radiation through the window, and a bleaching element located within the lamp body for emitting color-center bleaching radiation in response to the electric field degrading emission of the vacuum UV radiation, the bleaching radiation being in a frequency band (e.g., 5-6 eV) lower than the vacuum UV radiation.

Abstract: Gas detection electrochemical cell featuring, in one aspect, a liquid electrolyte free of any salt capable of dissociating to form in said electrolyte a weak acid or weak base (other than H.sub.3 O.sup.+ or OH.sup.-) which forms upon dissociation of the gas being measured.

Abstract: A method of detecting hydrogen cyanide using an electrochemical cell is disclosed. The cell comprises an electrolyte which is initially free of any salt capable of dissociating to form cyanide ions, a pH detection electrode and a reference electrode. A membrane permeable to hydrogen cyanide gas is used and the potential developed between the electrode is monitored as a measure of hydrogen gas partial pressure.

Abstract: Gas detection electrochemical cell featuring, in one aspect, a liquid electrolyte free of any salt capable of dissociating to form in said electrolyte a weak acid or weak base (other than H.sub.3 O.sup.+ or OH.sup.-) which forms upon dissociation of the gas being measured.

Abstract: A non-evacuated photodiode for detecting far-uv radiation. The photocathode is a cylindrical element surrounded by an annular anode. The photocathode is constructed of a metal (e.g., nickel) that emits electrons only in response to far-uv radiation of 140 nanometer or shorter wavelengths. A window (e.g., magnesium fluoride) is positioned at the entrance to the photodiode, to filter out far-uv radiation with wavelengths shorter than about 100 nanometers. The window and photocathode material serve to make the photodiode sensitive to radiation in a wavelength range to greater than 100 to 140 nanometers. A high-temperature perfluoroethylene material is used as an insulating layer for spacing the window from the anode and for spacing the anode from the photocathode. The photodiode is used in a gas chromatography detector.

Abstract: Electrochemical cell including an ion-specific membrane containing, in one aspect, Ag, S, and Sb and in another aspect a ternary compound of Ag, S and one of As, Sb, Se and Te. Methods are disclosed for making ternary compounds of Ag, S and one of Se, Sb, Te and As.

Abstract: An electrode arrangement for the detection of species ionized by radiant energy from a radiation source, comprising: an annular cathode; a shield, opaque to the radiant energy, extending across the cathode and having an aperture smaller than and coaxial with the annulus formed by the cathode; and an elongated anode having its distal end coaxially of the cathode and the shield aperture, the cathode being shielded from and the anode being exposed to the radiant energy from the radiation source.

Abstract: Apparatus for and method of photoinization in which a gas permeable membrane is extended across a chamber in a housing dividing said chamber into two subchambers, a ballast chamber having a gas inlet and a gas outlet on one side of said membrane, and a photoionization chamber having detection electrodes and a radiation source on the other side of said membrane, gases from a sample stream being diffused into said photoionization chamber through said membrane.