JPH0546500B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a total organic carbon concentration meter suitable for highly sensitive measurement of total organic carbon, which is one of the indicators of organic pollution of water.

Total organic carbon concentration meters are widely used for monitoring the quality of wastewater and managing the quality of recycled water. recently,
For the management of highly pure water used in the electronics industry, a total organic carbon concentration meter with unprecedented sensitivity is required.

Conventionally, there are various types of total organic carbon concentration meters, but they can be broadly classified into combustion type and wet oxidation type depending on the method of decomposing carbon compounds in sample water. The combustion type usually has a high-temperature combustion furnace for decomposing all the carbon components in the sample and a reaction tube for decomposing only the inorganic carbon components. For measurement, the sample is first injected into a high-temperature combustion furnace and brought into contact with a high-temperature oxidation catalyst to convert all carbon components into carbon dioxide gas, which is then sent to a carbon dioxide gas analyzer, such as a non-dispersive infrared analyzer, to determine the total carbon concentration. After measuring the inorganic carbon concentration, the inorganic carbon concentration was measured by injecting the sample into a reaction tube for decomposing only inorganic carbon and analyzing the generated carbon dioxide in the same way. This is to find the concentration. This method has the disadvantage that it cannot perform highly sensitive analysis because a large amount of sample cannot be injected.

On the other hand, the wet oxidation method adds an oxidizing agent such as persulfate or hydrogen peroxide to the sample, irradiates it with ultraviolet rays as necessary, oxidizes all carbon components, and guides the generated carbon dioxide gas to the analysis section. Measure the concentration, and calculate the inorganic carbon concentration in the same way from the amount of carbon dioxide produced under reaction conditions that decompose only the inorganic carbon component.
The total organic carbon concentration is measured from constant values on both sides. With this method, a large amount of sample can be injected, making it possible to increase sensitivity, but the decomposition reaction is complex, resulting in poor reproducibility and long measurement times.

SUMMARY OF THE INVENTION An object of the present invention is to provide a total organic carbon concentration meter that can eliminate these conventional drawbacks and perform highly sensitive measurements while keeping power consumption low.

The total organic carbon concentration meter of the present invention consists of a part that decomposes all carbon components by combustion and converts them into carbon dioxide gas, and a part that decomposes only inorganic carbon components to generate carbon dioxide gas (hereinafter referred to as these two parts that generate carbon dioxide gas). It belongs to the combustion type, which has a
It has the following characteristics.

The total organic carbon concentration meter of the present invention comprises: a sample reaction section that generates carbon dioxide gas from a sample; a trap for concentrating carbon dioxide gas that can temporarily trap the carbon dioxide gas;
The temperature of this trap for concentrating carbon dioxide gas is changed from room temperature to
It is characterized by having a heating device that can adjust the temperature up to 150°C or higher, and a carbon dioxide gas analysis section that measures carbon dioxide gas concentrated in the trap.

In the total organic carbon concentration meter of the present invention constructed in this manner, the carbon dioxide gas generated each time a sample is injected can be temporarily trapped in a trap for concentrating carbon dioxide gas provided at a subsequent stage. By rapidly heating this trap, the concentrated carbon dioxide gas is sent to the carbon dioxide analysis section, making it possible to measure low concentrations of carbon. The total carbon component and the inorganic carbon component are measured, and the concentration of the total organic carbon component can be determined from the difference. Therefore, even low concentrations of organic carbon can be measured.

In this case, measurement sensitivity can be increased not by injecting a large amount of sample at once, but by injecting small amounts many times to concentrate carbon dioxide gas, so the sample combustion section can be used for mass processing. There is no need to make it particularly large. As a trap for concentrating carbon dioxide gas, an adsorbent column that efficiently adsorbs carbon dioxide gas at low temperatures and efficiently desorbs carbon dioxide gas when heated is optimal. For example, molecular sieve 5A, a packing material for gas chromatographs, molecular sieve
13X etc. can be used.

Next, the present invention will be specifically explained using examples.

FIG. 1 is a block diagram showing an embodiment of the total organic carbon concentration meter of the present invention. In the figure, 1 is a carrier gas pump in the system, 2 is a flow meter, 3 is a sample reaction section, 4 is a sample reaction section heating temperature controller, and 5
1 is a reaction tube, 6 is a septum for sample injection, 7 is a trap for concentrating carbon dioxide, 8 is a heating device for desorbing carbon dioxide from trap 7, 9 is a filter and a dehumidifier, 10 is a carbon dioxide gas analysis section A non-dispersive infrared analyzer for measuring carbon dioxide concentration is used. 11
is an output amplifier, and 12 is a recorder. Also, the second
The figure shows another embodiment of the total organic carbon concentration meter of the present invention, which is equipped with flow path switching three-way sockets 14 and 15 so that a trap 7 for concentrating carbon dioxide can be introduced into the measurement flow path whenever necessary. ing. Further, in both figures, 13 is a carrier gas conduit, which is a Teflon pipe without adsorption. As trap 7 for carbon dioxide concentration, a glass tube with an outer diameter of 6 mm filled with 0.6 g of 30 to 60 mesh molecular sieve 5A for gas chromatographs was used, and a heating wire of 0.35 mm diameter was wound around it to generate approximately 600 W. This is used as a heating element and is used as a heating device 8
(using an EC7 temperature controller made by Okura Electric Co., Ltd.) to adjust the temperature of the trap 7 for carbon dioxide concentration from room temperature.
The temperature can be freely adjusted up to 400℃.

When the temperature of trap 7 was lower than 100°C, carbon dioxide gas was trapped in the molecular sieve and was not substantially eluted. Furthermore, at temperatures above 150°C, carbon dioxide gas elutes faster as the temperature increases. Therefore, when the sample is injected a required number of times from the sample injection septum 6, all of the carbon dioxide gas generated in the sample reaction section 3 is adsorbed by the trap 7, which is maintained at 100° C. or lower. Next, when the temperature of trap 7 is suddenly heated to a high temperature of 150°C or higher, preferably 250°C or higher,
All the adsorbed carbon dioxide gas is desorbed and analyzed in the analysis section 10.

The sample reaction section decomposes the total carbon component and the inorganic carbon component to generate carbon dioxide gas, which is measured using the above-mentioned apparatus, and the total organic carbon concentration can be determined by taking the difference between the measured values.

If trap 7 and heating device 8 are not provided,
When the sample injection amount was 20 μ, the detection limit for the total organic carbon concentration in the specimen sample was 0.5 mg/, but according to this example, when the sample injection number was 5 times, the detection limit was 0.1. mg/, and when it was done 10 times, it was 0.05 mg/. It was thought that increasing the number of injections would result in even higher sensitivity.

Also, between 5 and 7 in Figure 1 or 1 in Figure 2
It was more effective to install a dehumidifier similar to 9 between 4 and 7.

According to the present invention, highly sensitive measurement of total organic carbon can be carried out while keeping power consumption low.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are configuration diagrams showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Carrier gas supply pump, 2... Flow meter, 3... Sample reaction section, 4... Sample reaction section heating temperature controller, 5... Reaction tube, 6... Septum for sample injection, 7... ...Trap for carbon dioxide gas concentration, 8...
Heating device, 9...Filter and dehumidifier, 1
0... Carbon dioxide analysis section, 11... Output amplifier, 1
2...Recorder, 13...Carrier gas conduit, 1
4,15...Mikata Kotuku.

Claims (1)

[Claims] 1. In a total organic carbon concentration meter that burns or decomposes the total organic carbon in a sample to convert it into carbon dioxide gas and water, and measures the amount of carbon dioxide gas to measure the total organic carbon in the sample. A trap for concentrating carbon dioxide gas that can temporarily trap gas, a heating device that can adjust the temperature of the trap for concentrating carbon dioxide from room temperature to 150°C or higher, and a carbon dioxide analysis unit that measures carbon dioxide gas concentrated in the trap. A total organic carbon concentration meter characterized by having: