SU491090A1 - Electroconductometer detector for gas chromatography - Google Patents

Description

one

The proposed device relates to electrochemical type gas analyzers designed for analyzing mixtures containing trace substances that can form electrolytes either directly upon dissolution in water or after a corresponding chemical transformation.

Electroconductometric detectors are known which measure the electrical conductivity of water after dissolution of substances leaving the chromatographic column.

To increase the selectivity of the detection of hydrogen halides, nitrogen oxides, and sulfur dioxide (with respect to carbon dioxide), the contact time in the absorber is minimal. However, the detection selectivity is worse than the calculated one, determined from the data of solubility and conductivity of the detected substances for the equilibrium case, since the detector operates in streaming mode.

In addition, the mixing and separation of gas and water flows leads to instability of the fluid flow and increased fluctuations of the background current, which reduces the actual attainable sensitivity.

The design of the detector is complicated, since it is necessary to install devices regulating and stabilizing water consumption and a pump for pumping it.

In the proposed detector, these drawbacks are eliminated due to the fact that one of the electrodes of the measuring cell is made in the form of a cylinder located in the gas supply tube and connected according to the principle of a communicating vessel with a tank for supplying water.

The drawing shows the proposed detector.

The detector consists of an ion-exchange filter 1, a tube 2, supplying ion-free water to a cylindrical electrode 3, a measuring capillary 4, an electrode 5, a tap 6. A tube 7 leads to the analyzed gas from the reactor. A fitting 8 is supplied with a carrier gas to a gas pump consisting of a tank 9 and a vertical tube 10.

The detector works as follows.

The water level in the ion exchange filter 1 must be somewhat lower than the end of the electrode 3, but not lower than the level of the capillary rise of water in the electrode. Under the influence of the weight of the liquid column, the water, after cleaning in the filter, flows evenly through the capillary 4, passes the valve 6 and flows dropwise into the container 9. From here, water is supplied by the gas pump back to the filter 1. The gases from the reactor enter the tube 7, where wash the fixed surface of the water.

The impurities of hydrogen, nitrogen oxides and sulfur dioxide halo e1, dissolved in water, change its electrical conductivity and, therefore, the current through electrodes 3 and 5, which are connected to a constant voltage source and to the input of an electrometer.

Subject invention

Electroconductometric detector for gas chromatography containing tube

gas supply, tank for iodine water with an ion exchange filter and a two-electrode capillary measuring cell, which is also distinguished by the fact that, in order to increase the selectivity and sensitivity of detection, one of the measuring cell electrodes is made in the form of a cylinder located in the gas supply tube and a communicating vessel with a water supply tank.