JP5177095B2 - Sampling device with microsyringe having PTFE piston and total organic carbon measuring device - Google Patents

Description

  The present invention relates to a sample collection device including a syringe having a PTFE piston, and an all-organic carbon measurement device (also referred to as a TOC measurement device) as an example of an analysis device including such a sample collection device. . The total organic carbon measuring device measures total organic carbon content (TOC), total carbon (TC), or inorganic carbon (IC) in sample water.

  For the purpose of managing sample water with few impurities, such as pharmaceutical water, semiconductor manufacturing process water, cooling water, boiler water or tap water, TOC measurement of organic substances contained in such water is performed.

The TOC measuring device is equipped with an all-carbon combustion section containing an oxidation catalyst in a heating furnace, and the TOC in the sample water is changed to CO ₂ gas, and the CO ₂ concentration in the gas phase is measured by a non-dispersive infrared spectrophotometer. TOC measuring devices for measuring are widespread. In such a TOC measuring device, since the heating furnace of the all-carbon combustion unit is a heat source, even if the ambient temperature falls to, for example, 10 ° C. or less, the inside of the device is always in a heated state such as 20 ° C. or more. It is kept.

  On the other hand, an apparatus for measuring the TOC concentration while the sample water remains in a liquid phase has been developed. In such a liquid phase measuring apparatus, organic substances in sample water are converted into carbon dioxide in an oxidation reactor that oxidizes by irradiation with ultraviolet rays. The sample water remains in the liquid phase. The sample water is caused to flow through the sample water channel, the sample water channel and the measurement water channel through which the measurement water flows are brought into contact with each other through the gas permeable membrane, and carbon dioxide in the sample water is moved to the measurement water. Conductivity is measured by sending measurement water from which carbon dioxide has moved to a conductivity meter. By obtaining the relationship between the conductivity of the measurement water and the carbon dioxide concentration of the sample water in advance as a calibration curve, the carbon dioxide concentration of the sample water can be obtained from the measured conductivity of the measurement water (see Patent Document 1). .) The present invention is directed to an apparatus that oxidizes sample water by ultraviolet irradiation and measures the TOC concentration in the liquid phase as described above.

International Publication WO2008 / 047405 Pamphlet JP-A-2005-274483

  Since the TOC measuring apparatus that is the subject of the present invention does not include an internal heat source such as a heating furnace, the internal temperature of the apparatus decreases when the ambient temperature is as low as 10 ° C. or less. In order to collect sample water with the TOC measurement device and supply it to the analysis unit, the sample collection device includes a syringe that collects and supplies the sample water and a multiport valve that switches a flow path to be connected to the syringe. .

  An oven is provided for a portion that must be maintained at a constant temperature in the analyzer, for example, a column or detector of a liquid chromatograph, and the temperature is controlled so as to be a constant temperature. This is because the analysis result fluctuates due to changes in holding time or detection sensitivity due to fluctuations in temperature.

  However, the sample collection device used in the TOC measurement device and the like, which collects sample water and supplies it to the analysis unit does not affect the analysis result even if the temperature fluctuates.

  The syringe piston of the sampling device is made of PTFE (polytetrafluoroethylene). In the multi-port valve, the rotor is combined with the stator to which the flow path is connected, and the flow path is switched. However, some rotors have a sliding part made of PTFE with the stator.

  In such a TOC measuring device equipped with a syringe equipped with a PTFE piston and a PTFE rotor sliding part, when the temperature inside the device becomes a low temperature of 10 ° C. or less, the PTFE parts contract, A gap is formed in the sliding portion between the syringe cylinder and the sliding portion between the rotor and the stator of the multiport valve. When such a gap is formed, the sample water leaks from the gap. In addition, there is a problem that the accuracy of TOC measurement is lowered by the intrusion of air from the gap and the carbon dioxide gas in the air being dissolved in the sample water.

  An oven is provided for a portion that must be maintained at a constant temperature in the analyzer, for example, a column or detector of a liquid chromatograph, and the temperature is controlled so as to be a constant temperature. This is because the analysis result fluctuates due to changes in holding time or detection sensitivity due to fluctuations in temperature. However, the sample collection device that is used in the total organic carbon measurement device and collects the sample water and supplies it to the analysis section does not affect the analysis result even if the temperature fluctuates, so usually the temperature is not controlled. .

  An object of the present invention is to prevent a PTFE component from contracting even when the ambient temperature is lowered in a sample collection device for collecting sample water, and to prevent a gap from being generated in a sliding portion of the PTFE component. To do.

  The sample collection device of the present invention comprises at least a port connected to a flow path for supplying sample water to the stator, a port connected to the analysis device, and a common port connected by switching to these ports. The multi-port valve that rotates while the rotor slides and switches the flow path, and the common port of the multi-port valve are connected. The PTFE piston slides up and down in the cylinder to collect and send sample water. Syringe that performs the operation, a multiport valve support plate that supports the multiport valve, a syringe support plate that supports the syringe, and a relative position of the multiport valve and the syringe that supports both support plates A support mechanism consisting of a substrate that fixes the relationship, a syringe heater that heats the syringe, and the periphery of the syringe Detecting the temperature, the temperature is a temperature controller for heating the piston through the syringe with the energized heater when lower than a predetermined temperature.

  In the pulse-type flow-through photocatalyst evaluation apparatus, there is one in which a ribbon heater is wound around an injection port or a carrier gas PTFE tube and heated (see Patent Document 2). However, in Patent Document 2, the purpose of heating is to suppress the adsorption of contaminants, and has nothing to do with preventing liquid leakage or air intrusion.

  The mechanism for heating the piston via the syringe does not need to heat the entire sampling device, and only needs to be able to heat only the syringe. As a simple mechanism for that purpose, the syringe heater can be attached to the syringe support plate, and the syringe can be heated via the syringe support plate.

  When the sliding portion of the multiport valve with respect to the rotor stator is made of PTFE, it is preferable that a multiport valve heater is also attached to the multiport valve. In this case, the temperature control device controls the temperature so that both the syringe heater and the multiport valve heater are energized when the temperature around the syringe falls below a predetermined temperature.

The multiport valve heater need not be able to heat the entire sampling device, and only needs to be able to heat only the multiport. As a simple mechanism therefor, the multiport valve heater can be attached to the multiport valve support plate and heat the multiport valve via the multiport valve support plate.

  The TOC measuring device of the present invention is an example of an analyzer that uses the sampling device of the present invention. The TOC measurement device uses the sample collection device of the present invention as a sample collection device for collecting and supplying sample water. In addition to the sample collection device, the TOC measurement device is connected to the analyzer connection port of the sample collection device, The sample water supplied from the sampling device is oxidized by ultraviolet irradiation to convert it into carbon dioxide, and the sample water passage through which the sample water passed through the oxidative decomposition unit flows and the deionized water contains measurement water. A carbon dioxide separator having a measurement water flow channel, a gas permeable membrane interposed between the sample water flow channel and the measurement water flow channel, and a carbon dioxide separator capable of moving carbon dioxide; A conductivity measuring unit that measures the conductivity of the sample, and an arithmetic processing unit that includes a computing unit that calculates the TOC concentration of the sample water from the measurement value obtained by the conductivity measuring unit.

  Since the sampling device of the present invention is provided with a syringe heater that heats the cylinder in which the PTFE piston slides in the vertical direction, the PTFE piston can be prevented from contracting even if the ambient temperature is lowered. It is possible to prevent a gap from occurring on the sliding surface between the piston and the cylinder.

  The TOC measuring apparatus of the present invention that employs the sample collection device includes an error in the TOC measurement value due to leakage of sample water in the sample collection device or intrusion of carbon dioxide in the air into the sample water in the sample collection device. Can be prevented.

It is a schematic front view which shows the sample-collecting apparatus of one Example. It is a block which shows the total organic carbon measuring apparatus of one Example. It is a block diagram which shows the 3rd form of the oxidation decomposition | disassembly part, the carbon dioxide separation part, and the electrical conductivity measurement part in the all-organic carbon measuring apparatus of the Example.

One embodiment of the sampling device is shown in FIG.
The 8-port valve 2 which is a multi-port valve is attached to an aluminum multiport valve support plate 28, and the syringe 10 is attached to an aluminum syringe support plate 20. Since both support plates 28 and 20 are fixed to the substrate 8 and integrated, the relative positional relationship between the 8-port valve 2 and the syringe 10 is fixed. Both the support plates 28 and 20 and the substrate 8 constitute a support mechanism.

  The 8-port valve 2 includes a plurality of ports 6 in the stator 4. These ports 6 include at least a port connected to a flow path for supplying sample water, a port connected to an analyzer, and a common port switched to these ports. The stator 4 is rotatably provided with a rotor (not shown in the drawing). The rotor rotates while sliding with respect to the stator 4 to switch the flow path connected to the port.

  The syringe 10 is connected to a common port of the 8-port valve 2. The syringe 10 includes a PTFE piston 12 (see FIG. 2) that moves in the vertical direction while sliding on the cylinder inner surface. The piston 12 moves in the vertical direction while sliding in the cylinder to collect and send the sample water.

  The syringe 10 is provided with a syringe heater. The syringe heater may be a ribbon heater wound around the syringe 10, but in this embodiment, a cartridge heater 22 attached in close contact with the aluminum support plate 20 having good thermal conductivity is used. The syringe 10 is heated by the heater 22 through the support plate 20. The cylinder of the syringe 10 is made of glass having a lower thermal conductivity than metal, but can be heated via the support plate 20 to heat the internal piston. The support plate 20 may extend over the entire length of the cylinder of the syringe 10 or may be shorter than the length of the cylinder. Since the support plate 20 is made of aluminum, it has good thermal conductivity. Therefore, the heater 22 does not need to have a length that covers the entire length of the support plate 20, and only needs to be in contact with a part of the support plate 20.

  A temperature control device that detects the ambient temperature of the syringe 10 and energizes the heater 22 when the temperature drops below a predetermined temperature, for example, 10 ° C., and heats the piston therein via the syringe 10. It has. The temperature control device includes a temperature sensor 26 disposed at an appropriate position on the outer surface or inside of an analyzer such as a TOC measuring device in which the sampling device is disposed, and an ambient temperature detected by the temperature sensor 26 is a predetermined temperature. A control circuit 24 is provided to energize the heater 22 when the temperature is lowered. The energization control by the control circuit 24 is performed by passing a constant current through the heater 22. Since the temperature control of the syringe 10 does not need to be strict, if a current value that makes the temperature of the syringe 10 an appropriate temperature of about 20 to 30 ° C. is obtained in advance and set in the control circuit 24. Good. If a slight increase in cost is not a problem, a temperature sensor may be attached to the syringe 10 to control the current value so that the temperature of the syringe 10 becomes constant.

  The sliding portion of the rotor of the 8-port valve 2 with the stator 4 is made of PTFE. Therefore, a heater 30 such as a cartridge heater is also attached to the valve 2. The heater 30 is attached to the support plate 28 of the valve 2. Since the support plate 28 is made of aluminum having good thermal conductivity, the heater 30 does not need to have a length that extends over the entire length of the support plate 28, and may be in contact with a part of the support plate 28. The temperature control device including the temperature sensor 26 and the control circuit 24 also controls energization to the heater 30 for the valve 2. The control is performed simultaneously with the energization control with the heater 22 for the syringe 10. Control of energization of the heater 30 by the control circuit 24 is also performed by passing a constant current through the heater 30. Since the temperature control of the valve 2 does not need to be strict, if a current value is obtained in advance so that the temperature of the valve 2 becomes an appropriate temperature of about 20 to 30 ° C., it is set in the control circuit 24. Good. In this case as well, if a slight increase in cost does not become a problem, a temperature sensor may be attached to the valve 2 to control the current value so that the temperature of the valve 2 becomes constant.

  FIG. 2 schematically shows a TOC measuring apparatus according to an embodiment to which the sampling apparatus according to the embodiment of FIG. 1 is applied. A portion surrounded by a broken-line frame means that it is housed in the casing of the TOC measuring apparatus 100, and the outside of the broken-line frame indicates that it is outside the casing.

  A sample collection device 102 is provided in the TOC measurement device 100. The sample collection device 102 includes an 8-port valve 2 which is a flow path switching valve and a water collection syringe 10 connected to a common port of the valve 2. Connected to the syringe 10 is a gas supply channel 120 for supplying a gas not containing carbon dioxide into the syringe 10.

  One of the ports of the valve 2 is connected to a flow path 110 for taking sample water from the outside of the casing of the TOC measuring device, and the other port is a flow path 112 for taking pure water from the outside of the casing. Is connected to the other port, and a flow path 114 is connected to the other port for taking in the acid for making the sample water or pure water collected in the syringe 10 acidic. A flow path 116 connected to the oxidative decomposition unit 118 is connected to another port of the valve 2. Still another port of the valve 2 can be opened to the atmosphere.

  As the acid, an inorganic acid such as hydrochloric acid, sulfuric acid or phosphoric acid is used. It is preferable to adjust the pH of the sample water or pure water in the syringe 10 to 4 or less by adding an acid.

  The valve 2 is provided with a plurality of ports in the stator, and is switched so that the syringe 10 connected to the common port can be connected to any one of the ports by rotating the rotor.

  The syringe 10 can take sample water or pure water into the syringe 10 and further take an acid by sliding the piston 12 up and down while keeping the liquid tight inside the cylinder. Further, by pushing the piston upward, the collected sample water or pure water can be supplied from the flow path 116 to the oxidative decomposition unit 118 via the valve 2. The piston 12 is attached to the tip of the flanger 14. When the flanger 14 is driven by a syringe drive unit 109 driven by a motor, the piston 12 slides in the vertical direction within the cylinder.

  A gas supply flow path 120 that supplies a gas not containing carbon dioxide for aeration processing is connected to the syringe 10 at the lower end of the cylinder of the syringe 10. The position to which the gas supply channel 120 is connected is a position that is located above the piston 12 in a state where the piston 12 has moved to the lower end. The gas not containing carbon dioxide is, for example, high-purity air stored in a cylinder 119 or high-purity air supplied through a column filled with a filler that adsorbs carbon dioxide gas, but is not limited thereto. It is not something.

  The oxidative decomposition unit 118 is irradiated with ultraviolet rays while sample water or pure water (hereinafter simply referred to as pure water also includes pure water) flows through the flow path of the organic oxidation unit, and the organic matter in the sample water is oxidized and decomposed. It becomes carbon dioxide gas.

  The sample water that has passed through the oxidative decomposition unit 118 is guided to the carbon dioxide separation unit 124. In the carbon dioxide separator 124, the carbon dioxide component in the sample water moves into the measurement water through the gas permeable membrane. The sample water that has passed through the carbon dioxide separator 124 is discarded.

  The measured water that has passed through the carbon dioxide separator 124 is guided to the conductivity measuring unit 126. The conductivity measuring unit 126 includes an electrode that contacts the measurement water, and the conductivity of the measurement water is detected by the electrode. The conductivity of the measurement water changes depending on the concentration of the carbon dioxide component moved from the sample water to the measurement water in the carbon dioxide separator 124. Therefore, the carbon dioxide component of the sample water is based on the detected conductivity value of the measurement water. Can be determined. Since the carbon dioxide component is generated by oxidative decomposition of the TOC component in the sample water by the oxidative decomposition unit 118, the TOC concentration in the sample water can be obtained.

  The arithmetic processing unit 128 is connected to the electrode for measuring the conductivity of the conductivity measuring unit 126, and calculates the TOC concentration of the sample water based on the conductivity detected by the conductivity measuring unit 126.

  In this TOC measuring apparatus, the valve 2 is set so that the flow path 112 for taking pure water at the time of blank measurement is connected to the syringe 10, and the flow path 110 for taking sample water at the time of sample measurement is connected to the syringe 10. An appropriate amount, for example, 3 ml of pure water or sample water is collected in the syringe 10. Further, the valve 2 is switched so as to connect the syringe 10 to the port connected to the flow path 114 for supplying the acid, and the piston 12 of the syringe is further retracted to suck in a predetermined amount of the acid to obtain pure water or a sample. Adjust the pH of water to 4 or less. Thereafter, with the valve 2 switched to connect the syringe 10 to a port opened to the atmosphere, the piston 12 is retracted to the lower end. In this state, high-purity air is supplied from the flow path 120 into the syringe 10 at a flow rate of, for example, 100 ml / min for 90 seconds, and pure water or sample water collected in the syringe 10 is subjected to aeration treatment. Inorganic carbon contained in the sample water is released into the atmosphere and removed.

  After completion of the aeration process, the valve 2 is switched to connect the syringe 10 to the flow path 116, and pure water or sample water in the syringe 10 is supplied to the oxidative decomposition unit 118. In the oxidative decomposition unit 118, the organic carbon in the pure water or the sample water is oxidized and decomposed into carbon dioxide by the ultraviolet irradiation from the ultraviolet lamp. The pure water or sample water that has passed through the oxidative decomposition unit 118 is sent to the carbon dioxide separation unit 124. The pure water or the sample water comes into contact with the measurement water through the gas permeable membrane in the carbon dioxide separation unit 124 and the carbon dioxide moves to the measurement water, and the conductivity of the measurement water is detected by the conductivity measurement unit 126.

  Next, specific examples of the oxidative decomposition unit 118, the carbon dioxide separation unit 124, and the conductivity measuring unit 126 are shown in FIG.

  The oxidative decomposition unit 118 includes an organic matter oxidation unit 224 and an ultraviolet lamp 226. The organic oxidation unit 224 is made of a material that transmits ultraviolet rays, and includes a flow path through which sample water flows. The ultraviolet lamp 226 irradiates the sample water with ultraviolet rays from the outside of the organic oxidation unit 224. The organic matter oxidation unit 224 includes an ultraviolet irradiation unit that irradiates the sample water with ultraviolet rays from the ultraviolet lamp 226. While the sample water flows through the ultraviolet irradiation unit, the organic matter is oxidized by the ultraviolet irradiation to become carbon dioxide.

  The sample water that has passed through the oxidative decomposition unit 118 is supplied to a carbon dioxide separation unit 220 that is an example of the carbon dioxide separation unit 124. In the carbon dioxide separator 220, the sample water channel 202, the intermediate water unit 2044, and the measurement water channel 206 are stacked in a vertical direction and integrated with the intermediate water unit 204 interposed therebetween. The sample water that has passed through the organic oxidation unit 224 is caused to flow into the sample water channel 202. In the intermediate water portion 204, neutral water in a neutral region having a pH value higher than that of the sample water is poured or enclosed. The intermediate water section 204 is preferably a flow path through which intermediate water flows. Measurement water consisting of deionized water flows through the measurement water channel 206. The sample water flow path 202 and the intermediate water section 204 are in contact with each other through the gas permeable film 208, and the intermediate water section 204 and the measurement water flow path 206 are also in contact with each other through the gas permeable film 210. As the gas permeable membranes 208 and 210, a membrane having no selectivity for carbon dioxide, such as a porous membrane usually used for maintaining high-speed measurement, is used.

  As the carbon dioxide separation unit 220, a gas exchange unit on the sample water side and a gas exchange unit on the measurement water side are integrated here, but the gas exchange unit on the sample water side and the gas on the measurement water side are shown. The exchange parts may be separated from each other and the gas exchange parts may be connected by a flow path.

  Ion exchange water is supplied to the measurement water channel 206 of the carbon dioxide separator 220 as deionized water. As for the ion exchange water, pure water stored in the liquid reservoir 228 is sucked by the pump 232 and supplied to the measurement water flow path 206 of the carbon dioxide separation unit 220 through the ion exchange resin 230. The conductivity of the measured water that has passed through the measured water channel 206 is measured by a conductivity meter 234 that is the conductivity measuring unit 126. The electrical conductivity is the electrical conductivity of carbon dioxide that has moved from the intermediate water to the measurement water in the carbon dioxide separator 220. The measured water that has passed through the conductivity meter 234 is returned to the liquid reservoir 228 and reused. The conductivity meter 234 may be provided integrally with the carbon dioxide separator 220, or may be configured separately and connected by a flow path. The sample water that has passed through the sample water flow path 202 of the carbon dioxide separator 220 is discharged.

  Pure water or deionized water is supplied to the intermediate water channel 204 as intermediate water. The deionized water that has passed through the ion exchange resin 230 is also supplied as intermediate water. As the intermediate water, deionized water prepared using an ion exchange resin different from the measurement water may be used. The intermediate water comes into contact with the sample water through the gas permeable membrane 208 on the sample water flow path side, and also comes into contact with the measured water through the gas permeable film 210 on the measurement water flow path side.

  A common syringe pump is used to keep the flow rate ratio between the intermediate water flow rate and the measured water flow rate constant. What was supplied with the pump 232 via the same ion exchange resin 230 is used as intermediate water and measurement water. Measurement water flows from the measurement water channel 206 through the conductivity meter 234. The intermediate water is passed through the intermediate water flow path 204. Valves 248 and 250 are provided in the flow paths for returning the intermediate water and measurement water to the liquid reservoir 228, respectively, and two syringes 242 and 244 of one syringe pump 246 are respectively provided to adjust the respective flow rates. It is connected to the flow path. When flowing the intermediate water and the measurement water, the intermediate water and the measurement water are simultaneously sucked into the syringes 242 and 244 in a state where the valves 248 and 250 are closed, and flow rates determined by the inner diameters of the syringes 242 and 244, respectively. Intermediate water and measurement water are run. After completion of the measurement, the valves 248 and 250 are opened, and the syringe 242 and 244 are switched in the discharge direction, whereby the intermediate water and the measurement water sucked into the syringes 242 and 244 are returned to the liquid reservoir 228.

  In this way, when two syringes 242 and 244 are attached to one syringe pump 246 and the intermediate water discharged from the intermediate water flow path 204 and the measurement water discharged from the measurement water flow path 206 are sucked simultaneously, By selecting the diameters of the syringes 242 and 244, the flow rate ratio between the intermediate water and the measurement water can be maintained at a predetermined constant value. By maintaining the flow rate ratio between the intermediate water and the measurement water constant, the distribution ratio of the gas component from the intermediate water to the measurement water is maintained constant, and the reproducibility of the measurement is enhanced.

2 8 Port Valve 8 Substrate 4 Stator 6 Port 10 Syringe 12 Piston 20 Syringe Support Plate 22, 30 Heater 24 Control Circuit 26 Temperature Sensor 28 Multiport Valve Support Plate 100 TOC Measurement Device 102 Sampling Device 118 Oxidation Decomposition Unit 124 Carbon Dioxide Separation Unit 126 conductivity measuring unit 128 arithmetic processing unit

Claims (4)

At least a port connected to a flow path for supplying sample water to the stator, a port connected to the analyzer, and a common port that is switched and connected to these ports, and the rotor rotates while sliding relative to the stator A multi-port valve for switching the flow path , wherein the rotor has a sliding part made of PTFE with the stator; and
A syringe connected to the common port of the multi-port valve and collecting and feeding sample water by sliding a PTFE piston vertically in the cylinder;
Multiport valve support plate that supports the multiport valve, supports the syringe support plate that supports the syringe, and supports both support plates to fix the relative positional relationship between the multiport valve and the syringe. A support mechanism composed of a substrate,
A syringe heater for heating the syringe;
A heater for the multiport valve for heating the multiport valve;
Detects the temperature around the syringe, with its temperature heated the piston through the syringe by the energizing the two heater when lower than a predetermined temperature, said multi-port valve is also heated A temperature control device,
A sampling device comprising: The sampling apparatus according to claim 1, wherein the syringe heater is attached to the syringe support plate and heats the syringe through the syringe support plate. The sampling device according to claim 1 , wherein the multiport valve heater is attached to the multiport valve support plate and heats the multiport valve via the multiport valve support plate. A sampling device according to any one of claims 1 to 3 for collecting and supplying sample water;
An oxidative decomposition unit that is connected to the analyzer connection port of the sample collection device and oxidizes organic matter in the sample water supplied from the sample collection device to convert it into carbon dioxide by ultraviolet irradiation,
A sample water channel through which the sample water that has passed through the oxidative decomposition section flows and a measurement water channel through which measurement water made of deionized water flows are provided. A gas permeable membrane is interposed between the sample water channel and the measurement water channel, and the A carbon dioxide separator that is capable of transferring carbon;
A conductivity measuring unit for measuring the conductivity of measurement water from the carbon dioxide separation unit;
An arithmetic processing unit comprising an arithmetic unit for calculating the total organic carbon concentration of the sample water from the measured value by the conductivity measuring unit;
Total organic carbon measuring device.

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