RU2166753C2 - Procedure and device determining concentration of organic substances in liquid sample - Google Patents

Abstract

FIELD: instrumentation, analytic chemistry. SUBSTANCE: invention is meant to check content of organic pollutants in objects of environment, specifically, in natural water, in sewage or in technological solutions. Proposed procedure determining concentration of organic substances includes preliminary heating of liquid sample in atmosphere of inert gas and burning of it in mixture of oxygen and inert gas. Content of organic substances is found by quantity of oxygen spent for burning of liquid sample. Inert gas whole in proposed device into zone of preliminary heating of chamber of feed and burning of liquid sample and mixture of inert gas and oxygen is injected into zone of burning of liquid sample. EFFECT: usage of whole argon-oxygen mixture for analysis of burnt liquid sample, increased measurement accuracy. 2 cl, 1 dwg

Description

 The invention relates to the field of instrumentation in analytical chemistry and is intended to control the content of organic pollutants in environmental objects, in particular in natural and waste waters or technological solutions.

 A device for determining the total content of organic substances in water, in which a liquid sample is fed into the combustion chamber, and the combustion products are fed into a measuring cell with oxygen-ion conductivity / 1 /. The gas flow control means make it possible to divide the flow into two: one is fed through the combustion chamber to the measuring cell, and the second, bypassing the combustion chamber, directly to the measuring cell. Using the measuring cell, an electrical signal is recorded corresponding to the difference in oxygen in the two gas streams.

 The closest is a method and apparatus for determining the total organic matter content in water, including a dosed oxygen supply unit, a liquid sample supply unit, a liquid sample inlet and combustion chamber with a liquid sample inlet located in a coaxial furnace, and a solid electrolyte measuring cell with oxygen-ion conductivity installed in a coaxial furnace, a unit for regulating stabilization and measuring air flow, measuring and registration unit / 2 /. The method consists in determining the total content of organic substances in water by burning a sample in a stream of an inert gas and oxygen mixture and then determining the content of the determined organic substances by changing the oxygen content using a solid electrolyte cell with oxygen-ion conductivity using a coulometric solid electrolyte cell to determine the change in oxygen content, the pre-selected analyzed sample is burned in the gas mixture flow; the time is determined changes in oxygen concentration and the magnitude of the maximum change in oxygen concentration. Then, the oxygen concentration in the gas mixture is set equal to the maximum change in the oxygen concentration, the analyzed sample is introduced into the low-temperature zone of the combustion chamber, the latter is kept for the time necessary to reach the set oxygen concentration, followed by burning of the sample in the high-temperature zone of the combustion chamber, the amount consumed to burn oxygen, while the content of organic substances in the water is judged by the value of a certain amount but oxygen.

 The disadvantage of this method and device is the change (decrease) in the oxygen content in the gas mixture during the evaporation of water in a liquid sample, which leads to a systematic error and reduces the accuracy of the determination of organic matter in the analyzed sample.

 The aim of the proposal is to eliminate these drawbacks, namely the use of the whole argon-oxygen mixture for the analysis of the burnt sample and to increase the accuracy of measurements.

 The goal is achieved by the fact that in the proposed method and apparatus for determining the concentration of organic substances in a liquid sample, in an inlet and combustion chamber of a liquid sample, an inert gas is supplied to the preheating zone where water begins to evaporate, and a mixture of inert gas and oxygen is supplied to the combustion zone of the sample . The drawing shows a block diagram of a device that implements the proposed method for determining the concentration of organic substances in a liquid sample. It contains means for supplying an inert gas 1, means for regulating the gas stream 2 and 3, means for dispensing oxygen into the gas stream 4, an input and burning chamber 5, a cell with a liquid sample 6, a measuring cell with oxygen-ion conductivity 7, and an amplifier 8, means stabilization of gas flow 9, and means for pumping gas 10 from the input and combustion chamber 5.

 The gas flow control means 2 and 3 provide a separation of the flow from the inert gas supply means 1. The oxygen dosing means 4 provides the necessary oxygen concentration in the argon stream. The input and combustion chamber 5 has three zones: a liquid sample inlet zone, a preheating zone connected to an inert gas supply means 2, a liquid sample combustion zone with oxygen dosing means in an inert gas stream. The cuvette 6 is installed in the injection zone of the liquid sample and can be moved to the preheating zone and to the combustion zone of the input and combustion chamber. The measuring cell with oxygen-ionic conductivity 7 is connected by a pipeline to the combustion zone of the input and combustion chamber 5 and with means for stabilizing the flow of gas 9 and with means for pumping gas 10.

 The method for determining the concentration of organic substances is that the preliminary heating of the liquid sample is carried out in an inert gas environment and the evaporated water together with the inert gas enters the combustion zone of the input and combustion chamber, where the liquid sample is burned in an inert gas-oxygen mixture. Using a measuring cell with oxygen-ionic conductivity and a differential amplifier, the amount of oxygen in a mixture of argon and oxygen used to burn a liquid sample is measured and the content of organic substances in the liquid sample is determined.

 The device operates as follows. A liquid sample is poured into the cell 6 through the inlet opening, then the cell with the liquid sample is moved to the preheating zone. Inert gas enters the pre-heating zone of the inlet chamber, where it is divided into two streams: one is directed to the sample inlet zone and prevents atmospheric air from entering the liquid sample through the inlet of the liquid sample; the other is directed to the combustion zone of the liquid sample, providing water vapor released in the preheating zone to the combustion zone and then to the measuring cell with oxygen-ion conductivity 7. The signal from the measuring cell is fed to the input of the differential amplifier 8. Pumping the gas mixture from the chamber input and combustion 5 is carried out through means for stabilizing the flow of gas 9 and means for pumping gas 10.

Literature
1. GB N 1446827, cl. G 01 N 27/46, op. 1976.

 2. RU 2053507 C1, cl. G 01 N 27/417, op. 1996.

Claims (2)

 1. The method of determining the concentration of organic impurities in a liquid sample, which consists in pre-heating the liquid sample and burning the liquid sample in a mixture of inert gas and oxygen, followed by analysis of the combustion products, characterized in that an inert gas stream is introduced into the zone of preliminary heating of the liquid sample, and the liquid sample combustion zone is an inert gas stream with oxygen.  2. The device for implementing the method according to claim 1, comprising a sequentially located combustion zone of the input and combustion chamber and a measuring cell with oxygen conductivity, characterized in that it is equipped with a pre-heating zone of the input and combustion chamber connected to an inert gas supply means to it and located in front of the combustion zone of the liquid sample, which is connected to the means for dispensing oxygen into the gas stream.