Abstract: The stability of a cholinesterase (particularly a cholinesterase solution impregnated into a porous material and air-dried) can be improved by: (a) buffering the cholinesterase solution with a zwitterionic buffer, e.g. a buffer having a sulfonic acid group and a protonatable amine group, and, preferably, (b) further drying the impregnated, air-dried porous material under a high vacuum (e.g. 0.01 mm Hg or less) at normal ambient temperatures. The most useful porous materials are sheet-like in nature; that is, they have only two major surfaces. An impregnated, sheet-like material of this invention can be used in a cholinesterase inhibitor detector kit. A typical kit of this type provides a simple means for detecting, inter alia, environmental cholinesterase-inhibiting pollutant, e.g. organophosphorous pesticides and nerve agents.

Abstract: A gas sensor unit designed to indicate the presence of hydrocarbon vapors but be insensitive to carbon monoxide. The unit comprises two TGS sensors, one covered by a semi-permeable membrane and the other uncovered; the uncovered sensor responds to both crude oil and carbon monoxide, the covered sensor responds only to carbon monoxide. In one embodiment, the two sensors are connected in series; the total response of both sensors and the difference in response between the two sensors are measured, and changes in the parameters indicate the presence of an oil spill. In another embodiment, each sensor's output is compared with its reference voltage; if the uncovered sensor has an output that is higher than its reference while the covered one does not, the presence of an oil spill is indicated.

Abstract: Air that is desired to be examined for impurities is drawn through a concentrator comprising a cylindrical receptacle into which the air is introduced at the base portion of the receptacle in a direction tangentially of the cylindrical wall. A scrubbing liquid such as water is supplied to the receptacle and withdrawn therefrom on a continuous basis. The quantity of water only partially fills the region at the base of the receptacle where the air is tangentially introduced, with the result that the water is caused to rotate vigorously within the cylindrical wall as a thin film. The air is initially beneath the rotating film but then passes upwardly through it and is efficiently scrubbed. Gaseous and particulate impurities in the air are thus extracted into the water, and the same is drained from the receptacle and monitored for contaminant content.