Abstract: A disposable sensor for metal analysis comprises a housing including a first section, a second section, and a flexible intermediate section therebetween. An ampoule containing a reagent is disposed in the intermediate section. A liquid seal is formed between the first and second sections. The intermediate section of the housing of the disposable sensor may be flexed to break the ampoule. When the seal is broken between the first and second sections, and the water (or any other liquid) sample mixes with the reagent, the mixture flows into the second section containing an electrode assembly. The electrode assembly may be disposed in engagement with the monitoring device to determine the concentration of the at least one metal in the water (or any other liquid) sample.

Abstract: In an apparatus for an air sample analysis, employing a dual polarity Ion Mobility Spectrometer (IMS), a method for stabilizing equilibrium conditions associated with the switching of the electric fields in the IMS cell comprises the steps of modulating a duty cycle of the electric field at the shutter grid located between the reactor region and the drift region of the IMS cell. During the switching of the electric fields at the cell, the open time of the duty cycle of the electric field at the shutter grid is extended. After the background polarity has been switched to the opposite polarity, the open time is returned to its normal value.

Abstract: In an apparatus for detecting alarm molecules, residual alarm molecules are automatically removed during a clear-down mode before a subsequent air sample is to be introduced. The apparatus comprises a detector unit, a sensor unit and a filtering sub-unit including a pump and a filter. During a challenge, the pump in the sub-unit is turned off, and the air sample passes from the inlet port of the first unit through the second unit to the output port of the first unit, thereby depositing alarm molecules in the first unit and the second unit. During the clear-down mode, the pump in the sub-unit is turned on, and outside air enters through the output port of the first unit, mixes with air flow from the output of the second unit, and passes through the sub-unit. Filtered air from the sub-unit exhausts the first unit through the inlet port of the first unit and passes into the second unit, thereby cleaning the first unit and the second unit from the alarm molecules deposited therein during the challenge mode.

Abstract: An improved photoionization ion mobility spectrometer is disclosed which utilizes a flashlamp as the source for ionization. A gas sample is introduced via a carrier gas into a ionization chamber which is part of the spectrometer cell. Ionizable molecules contained in the injected gas sample are ionized by the ultraviolet light emitted from the flashlamp. The ionized molecules are attracted by an electrostatic drift field into a drift chamber and travel therethrough against the flow of a drift gas counter-current thereto until they are captured by a collector located in the drift chamber opposite to the ionization chamber. A dopant with an effective ionization potential lower than the photon energy of the emitted light can be introduced into the ionization chamber to further improve the sensitivity and specificity.

Abstract: An improved ion mobility spectrometer (IMS) and method for operating the same which enables analysis of chlorine dioxide in a mixture of gases which also includes the interferant chlorine. A controlled concentration of an amine such as methylamine is added to the air carrier gas stream prior to application of the carrier gas stream. The amine suppresses the chlorine peak, thereby improving the specificity of the IMS to chlorine dioxide. The IMS of the present invention also includes an improved membrane filter for pre-filtering chlorine, and a software algorithm for accommodating peak drift.

Abstract: An improved ion mobility spectrometer (IMS) and method for operating the same which enables analysis of ammonia in a mixture of gases when air is used as the carrier gas and the drift gas in the IMS. A controlled concentration of an ester such as Dimethyl methyl phosphonate (DMMP) is added to the air carrier gas stream prior to application of the carrier gas stream. The DMMP clusters with the ammonia, and the drift times of the ionized clusters differ from the drift times of the ions generated from the other constituents of the sample, thereby enabling identification and quantification of the ammonia.

Abstract: An improved ion mobility spectrometer (IMS) and method for operating the same which enables analysis of a specific acid gas analyte in a mixture of such gases when air is used as the carrier gas and the drift gas in the IMS. A controlled concentration of sulfur dioxide dopant is added to the air carrier gas stream prior to application of the carrier gas stream. In the IMS, the drift times of the ions generated from the doped air carrier gas differ from the drift times of the ions generated from the acid gas analyte, thereby enabling identification and quantification of the analyte.

Abstract: A system for and a method of increasing the sensitivity of organic vapor detection in ion mobility spectrometer by as much as three (3) orders of magnitude. Vapors are collected from the gas to be analyzed by controlled adsorption and are subsequently thermally released as an enriched concentration into the reactor volume of an ion mobility spectrometer. The herein disclosed system of preconcentrator and ion mobility spectrometer is easier to maintain and is more portable than other instruments of comparable sensitivity and the reliable operation is simpler. In one experiment, the computed enrichment factor of 3,500 for the preconcentrator lowered the limit of detection from 10 ppt for the ion mobility spectrometor alone down to 0.003 ppt for the embodiment of this invention. The sensitivity, compactness, ease of operation and ruggedness make the invention a suitable choice as a sensitive, efficient, and rapid detector of narcotics, toxic and explosive materials.

Abstract: An ion mobility spectrometer, ionization detector and mass spectrometer is described having a reaction region, and a region for introducing a sample gas, liquid or solid samples into the reaction region and an electrolyte in the reaction region of an alkali salt heated to a predetermined temperature, such as room temperature to 1000.degree. C., to provide a chemical reaction between the alkali atoms, cations or complement anions with the sample to provide product ions. The invention provides a non-radioactive ionization source for ionization of a broad class of compounds.

Abstract: An improved method for operating an ion mobility spectrometer (IMS) to enable detection of an acid gas analyte when air is used as the carrier gas and the drift gas in the IMS. A controlled concentration of a dopant substance is added to the air carrier gas stream prior to application of the carrier gas stream. In the IMS, the drift times of the ions generated from the doped air carrier gas differ from the drift times of the ions generated from the acid gas analyte, enabling the identification and quantification of the analyte. The dopants comprise substituted phenol compounds, with methyl salicylate (MS) or 2-hydroxyacetophenone (2-HAP) being preferred.

Abstract: An ion mobility spectrometer is described for detecting sample gas in a carrier gas incorporating a block of ceramic material having a passageway wherein the passageway contains an ionization source, a resistive material on the walls of the passageway prior to and after a shutter grid to form a reaction region and drift region respectively, an aperture grid and a collector. A radioactive or non-radioactive ionization source may be inserted into one end of the passageway while the aperture grid and collector may be inserted into the other end and rigidly positioned with respect to the block of ceramic material. The invention simplifies the exchange of the ionization sources where it may be either radioactive or non-radioactive, and improves the assembling and sealing of the ion mobility spectrometer cell.

Abstract: A method for operating an Ion Mobility Spectrometer in which an analyte sample is ionized in the spectrometer reaction chamber and the analyte ions are permitted to flow freely from the reaction chamber into the spectrometer drift chamber. The ion current output from the spectrometer ion current detector is observed during this time. The ion flow from the reaction chamber to the drift chamber is then momentarily interrupted and the time delay between the time of ion flow interruption and the appearance of a decrease in the ion current detector output is observed. Different substances are characterized by different delays. The concentrations of the different substances may be determined by measuring the change in detected ion current after the ion flow interruption.

Abstract: The present invention provides a process for building an immobilized structure comprising multiple monolayers of effective sequential polymeric linkages. The multiple monolayers are built, monolayer by monolayer, from the surface of a solid phase, by an alternating reaction sequence conducted with multifunctional reagents. The process provides the capability of building numerous immobilized multiple monolayer structures wherein the length of each structure extending from a solid phase is substantially the same. Structures comprising multiple monolayers of polymeric linkages are useful for many purposes, as for example, immobilizing macromolecules or other biomolecules and the like to produce chemical or biochemical sensors. Other uses extend to molecular electronic applications, such as the production of molecular conductive wires and molecular circuitry.

Abstract: A thermionic emitter for providing positive ions has been described incorporating a mixture of beta-alumina and inert material such as charcoal positioned on a filament for heating the mixture. Alternately the invention may incorporate beta-alumina with inert material such as nickle deposited in selected areas. The invention overcomes the problem of generating positive ions with low power consumption.