An apparatus and method for the measurement of low levels of carbon dioxide in a sample employing membrane separation and ion-exchange technology. The difference in acid strength of carbonic acid and other acids is exploited by first treating the sample with a weak base in a membrane separator and then with a strong base in the membrane separator. In this manner, the carbonic acid is distinguished from the stronger acids. By converting carbonic acid to sodium carbonate, the conductivity level is enhanced facilitating more precise measurements.

A measuring circuit for use with an active polarized electrode, a reference electrode and a diaphragm which separates the solution to be examined from the electrolyte in which the electrodes are immersed. The output signals from the polarized electrode and from the reference electrode are processed as follows. The respective electrode is connected to one of the inputs of a respective operational amplifier (OA1, OA2) which serve as current voltage converters. The outputs of these amplifiers are then connected to a third operational amplifier (OA3) which detects the prevailing current difference in the electrode currents and initiates a necessary correction.

A method and apparatus wherein a sample of gas or fluid containing carbon dioxide in the form of dissolved carbon dioxide gas, bicarbonate ion, and/or carbonate ion is injected into an extraction chamber provided with an acid extracting fluid. A carbon dioxide-free gas stream is passed through the extraction chamber in order to carry the dissolved CO.sub.2 gas formed from bicarbonate and carbonate ions, as well as that already present, onto a spiral absorbing column, wherein a dilute alkaline solution absorbs the CO.sub.2 with a resulting change in electrical conductivity of the alkaline solution. The system disclosed provides electrical means for measuring the conductivity difference thus produced, means for conversion of this difference to an appropriately coded electrical signal, and means for providing a direct display of the sample concentration. Means are provided for indicating when a sample is being processed by the apparatus, and for holding the displayed concentration until manually re-set. Two types of extraction chambers are disclosed, one for gas and non-foaming liquids, and a second for foaming liquids such as blood. The method and apparatus is suitable for use with samples containing as little as 20 nano-Moles (10.sup.-9 Moles) of carbon dioxide in all forms.

An apparatus and method for the measurement of low levels of carbon dioxide in a sample employing membrane separation and ion-exchange technology. The difference in acid strength of carbonic acid and other acids is exploited by first treating the sample with a weak base in a membrane separator and then with a strong base in the membrane separator. In this manner, the carbonic acid is distinguished from the stronger acids. By converting carbonic acid to sodium carbonate, the conductivity level is enhanced facilitating more precise measurements.

A device or system for monitoring for the presence of leaks from a hazardous fluid is disclosed which uses two electrodes immersed in deionized water. A gas is passed through an enclosed space in which a hazardous fluid is contained. Any fumes, vapors, etc. escaping from the containment of the hazardous fluid in the enclosed space are entrained in the gas passing through the enclosed space and transported to a closed vessel containing deionized water and two electrodes partially immersed in the deionized water. The electrodes are connected in series with a power source and a signal, whereby when a sufficient number of ions enter the water from the gas being bubbled through it (indicative of a leak), the water will begin to conduct, thereby allowing current to flow through the water from one electrode to the other electrode to complete the circuit and activate the signal.