JP2015187595A - analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the life of an analyzer performing a step of collecting heated alkaline solution into a glass container, by preventing melting of the glass container due to the alkaline solution.SOLUTION: It becomes possible to prevent melting of glass due to alkaline solution, thereby improving the life of a glass container 11a, by heating and reacting an alkaline solution containing a sample in a reaction chamber 2 and collecting the reacted solution into the glass container 11a communicating with the reaction chamber 2 at a fluid passage P4 to analyze the sample while providing a cooling device 13 on the fluid passage P4 and cooling the solution in the passage P4 by the cooling device 13.

Description

  The present invention relates to an analyzer, and more particularly to an analyzer including a step of collecting an alkaline solution heated during a cycle of an analysis operation into a glass container.

  For example, in some types of analyzers such as a total nitrogen / total phosphorus meter (TN / TP analyzer), an alkaline solution containing the sample is heated and reacted during the cycle of the analysis operation, and the solution is collected in a glass container. There is a thing including the process to do.

  In other words, in order to measure the total nitrogen and total phosphorus contained in wastewater, etc., when measuring total nitrogen with a total nitrogen / total phosphorus meter based on the ultraviolet absorptiometry, the sample to be analyzed is generally used. A sodium hydroxide aqueous solution and a potassium peroxodisulfate aqueous solution were added, and these were placed in a reaction vessel and heated while being irradiated with ultraviolet rays, thereby causing an ultraviolet oxidative decomposition reaction. All the nitrogen compounds to be converted into nitrate ions. The solution after the reaction is sucked from the reaction tank with a syringe pump, adjusted to pH with hydrochloric acid, sent to an absorbance measurement cell, irradiated with ultraviolet light having a wavelength of 220 nm, which is an absorption peak of nitrate ions, and the absorbance. From this, the amount of total nitrogen in the sample is measured (see, for example, Patent Document 1).

  In the above analysis cycle, the alkaline solution containing the sample in the reaction tank is usually heated to about 80 ° C., and a syringe pump barrel for sucking the solution is often made of glass.

JP 2007-060441 A

  By the way, when total nitrogen is measured with a total nitrogen / total phosphorus meter, an alkaline solution containing a sample heated to about 80 ° C. in a reaction vessel is collected in a glass barrel of a syringe pump. However, when the glass barrel is eluted for this reason and the glass barrel is used for a relatively long period of time, the elution of the glass progresses and liquid leakage or devitrification progresses, and there is a possibility that it may be necessary to replace it below the original device life. .

  An object of the present invention is to provide an analyzer capable of suppressing the elution of glass by such an alkaline solution and thus improving the lifetime of the apparatus.

  In order to solve the above-mentioned problems, the analyzer of the present invention is made of a glass-made solution in which an alkaline solution containing a sample is heated and reacted in a reaction vessel, and the solution after the reaction is communicated with the reaction vessel through a liquid channel. An analyzer that is collected in a container and used for analysis of a sample is characterized in that a cooling device that cools the solution flowing in the liquid channel is provided on the liquid channel.

  Here, the present invention can be applied to a total nitrogen / total phosphorus meter. As a specific configuration in such a case, the reaction vessel includes a sample, an aqueous solution of sodium hydroxide and an aqueous solution of potassium peroxodisulfate at the time of measuring total nitrogen. It is a reaction vessel for causing a reaction based on the ultraviolet oxidative decomposition method by irradiating ultraviolet rays while heating in a housed state, and the glass container contains a sample, an aqueous solution of sodium hydroxide and an aqueous solution of potassium peroxodisulfate. A glass barrel of a syringe pump for weighing and injecting into the reaction vessel and sucking the solution after the reaction in the reaction vessel and delivering it to the absorbance measurement cell. It is possible to adopt a configuration in which the cooling device is provided on a pipe connecting the reaction tank and the reaction tank.

  In the present invention, since the degree of elution of glass by the alkaline solution depends on the temperature of the alkaline solution, when the solution heated in the reaction vessel is collected in a glass container, the solution is cooled in the flow path. So, we are going to solve the problem.

  Here, the graph showing the relationship between the erosion depth and temperature when glass (borosilicate glass) is immersed in 1 mol / l of sodium hydroxide aqueous solution for 1 hour is illustrated in FIG. As shown in the graph, the alkaline solution elutes more glass as its temperature increases. Therefore, before collecting the alkaline solution heated in the reaction vessel in a glass container, a cooling device is provided on the liquid flow path connecting them to reduce the temperature of the alkaline solution, thereby suppressing elution of the glass container. can do.

When the present invention is applied to a total nitrogen / total phosphorus meter, a space between a reaction tank that causes an ultraviolet oxidative decomposition reaction and a syringe pump that sucks a solution from the reaction tank and sends it to an absorbance measurement cell. By disposing the cooling device on the pipe that becomes the liquid flow path to be connected, elution of the syringe barrel made of glass can be suppressed.
In addition, at least a flow path for introducing a sample, a flow path for introducing an alkaline solution, a flow path connected to the reaction layer, and a solution after the reaction are measured in the liquid flow path between the reaction layer and the glass container. A ceramic valve that connects each flow path including the flow paths in a switchable manner may be provided, and the ceramic valve may also serve as a cooling device.

  According to the present invention, the cooling device is provided on the liquid flow path for collecting the alkaline solution heated in the reaction vessel into the glass container, and the temperature is lowered before the alkaline solution flows into the glass container. In addition, the elution of the glass by the alkaline solution can be suppressed, and the life of the apparatus can be extended.

  In addition, since the present invention only requires an appropriate cooling device on the liquid flow path, it can be easily improved over existing analyzers.

The schematic block diagram which shows embodiment of this invention. The schematic diagram explaining the principal part structure which shows other embodiment of this invention. The graph showing the relationship between the erosion depth at the time of glass immersion in an alkaline solution, and temperature. The schematic block diagram which shows other one Embodiment of this invention. The schematic sectional drawing of the ceramic valve in FIG. The graph which shows the experimental data of the thermal radiation effect at the time of using a ceramic valve for the apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an embodiment in which the present invention is applied to a total nitrogen / total phosphorus meter 100.

  The online sample is a sample such as factory effluent to be analyzed, and is automatically collected at set intervals and taken into the analyzer through the online sample introduction pipe P1. In addition, an off-line sample collected by an arbitrary technique is taken into the analyzer through the off-line sample introduction tube P2.

  Each of these introduction pipes P1 and P2 is connected to each individual distribution port (1) and (2) of a first 8-port valve 1 made of PTFE (polytetrafluoroethylene). The other distribution ports (3) to (8) of the port valve 1 include a reaction tank 2 for causing a reaction based on the ultraviolet oxidative decomposition method, a measurement cell 3 for measuring the absorbance based on the ultraviolet absorptiometry, and the like. Is connected. In addition, the solution which passed through the reaction tank 2 is processed as a waste liquid by the discharge pump 4.

  The common port (0) of the first 8-port valve 1 is connected to the distribution port <1> of the second 8-port valve 5 made of PTFE by a pipe P3. The other distribution ports <2> to <7> of the second 8-port valve 5 include a sodium hydroxide aqueous solution 6 and a potassium peroxodisulfate aqueous solution 7 which are reagents used for measuring total nitrogen, and pH adjustment. Hydrochloric acid 8 or the like is connected. The second 8-port valve 5 and the distribution port of the first 8-port valve 1 are connected to a reagent group for measuring total phosphorus, a standard sample, and a drain switching valve 9, a sample switching valve 10, and the like. However, since these are not directly related to the characteristics of the present invention and are well known, detailed description thereof is omitted here.

  A syringe pump 11 is connected to the common port <0> of the second 8-port valve 5, and this syringe pump 11 has a glass barrel 11 a, and the inside can be stirred by the stirring pump 12. It can be done.

  A feature of this embodiment is that a cooling device 13 is provided on a pipe P4 that communicates the reaction tank 2 with the first 8-port valve 1. The cooling device 13 is not particularly limited, such as an air-cooled type using a fan or a water-cooled type using a water tank, and a solution of about 70 to 80 ° C. flowing inside the pipe P4 from the outside. Can be cooled to a predetermined temperature or lower, for example, 55 ° C. or lower.

  In the above embodiment, the operation of total nitrogen measurement will be described. First, the first 8-port valve 1 and the second 8-port valve 5 are driven, and either the online sample introduction pipe P1 or the offline sample introduction pipe P2 is operated. Is communicated with the syringe pump 11, and the syringe pump 11 is driven in this state, and a specified amount of sample is collected in the glass barrel 11 a. Next, by appropriately driving the second 8-port valve 5 and the syringe pump 11, a predetermined amount of each of the aqueous sodium hydroxide solution 6 and the aqueous potassium peroxodisulfate solution 7 is collected in the glass barrel 11a and stirred. Stir with pump 12. Thereafter, the first 8 port valve 1 and the second 8 port valve 5 are driven to connect the syringe pump 11 and the reaction tank 2, and the solution in the glass barrel 11 a is sent into the reaction tank 2 by driving the syringe pump 11. To do.

  In the reaction tank 2, the sample produced and sent as described above, that is, an alkaline solution composed of the aqueous sodium hydroxide solution 6 and the aqueous potassium peroxodisulfate solution 7 is heated to a prescribed temperature (for example, 80 ° C.) while being heated to ultraviolet light. Is irradiated with UV to cause an ultraviolet oxidative decomposition reaction, and all nitrogen compounds contained in the sample are converted to nitrate ions.

  Thereafter, the first 8-port valve 1 and the second 8-port valve 5 are driven, the reaction tank 2 and the syringe pump 11 are connected, and a predetermined amount of the solution in the reaction tank 2 is collected in the glass barrel 11a. The two-port valve 5 is driven to collect hydrochloric acid 8 in the glass barrel 11a, pH is adjusted, the first eight-port valve 1 and the second eight-port valve 5 are driven again, and the syringe pump 11 and the absorbance are measured. The measurement cell 3 is communicated, the solution in the glass barrel 11a is sent into the measurement cell 3, and the absorbance is measured by irradiating light with a wavelength of 220 nm. From the measurement results, the amount of nitrate ions in the solution, and hence the total amount of nitrogen present in the sample, is determined.

  In the above operation, when the solution heated in the reaction tank 2 is collected in the glass barrel 11a of the syringe pump 11 through the pipe P4, the solution is strongly alkaline and heated to about 80 ° C. If collected in the glass barrel 11a as it is, the glass in the barrel 11a is eluted. However, in the present invention, by providing the cooling device 13 on the pipe P4, the solution flowing in the pipe P4 is cooled to 55 ° C. or less, so that there is almost no possibility of elution when flowing into the glass barrel 11a. (See FIG. 3).

  Here, in the above embodiment, the example in which the present invention is applied to the total nitrogen / total phosphorus meter 100 has been shown, but the present invention is not limited to this, and the alkali heated to about 55 ° C. or more. The present invention can be widely applied to analyzers including a step of collecting a solution in a glass container.

  That is, as schematically shown in FIG. 2A, in an analyzer having a step of collecting an alkaline solution heated in a reaction vessel 101 into a glass container 103 through a liquid channel 102 such as a pipe. As shown in FIG. 5B, a cooling device 104 is provided on the liquid flow path 102 to cool the solution flowing in the liquid flow path 102, so that the glass container by the solution flowing into the glass container 103 is used. 103 elution can be suppressed and the life of the glass container 103 can be extended.

  Next, a modified embodiment of the above-described total nitrogen / total phosphorus meter will be described. FIG. 4 is a schematic configuration diagram of a total nitrogen / total phosphorus meter 101 according to another embodiment of the present invention. The difference from the total nitrogen / total phosphorus meter 100 shown in FIG. 1 is that the cooling device 13 provided on the pipe P4 between the reaction tank 2 and the first 8-port valve 1 is eliminated, and the PTFE made in FIG. Instead of the first 8 port valve 1 and the second 8 port valve 5, the first 8 port valve 1 a and the second 8 port valve 5 a made of ceramic are used, and these are also used as the cooling device 13. In addition, since it is the same as that of the total nitrogen / total phosphorus meter 100 described above about other components, a part of the description is omitted by attaching the same reference numerals.

As shown in the schematic cross-sectional view of FIG. 5, the ceramic valves 1 a and 5 a used here are composed of a stator 21 and a rotor 22 formed of ceramic blocks. The stator 21 has a hole 23 communicating with the common port <0> and eight holes 24 communicating with the respective distribution ports <1> to <8>. The rotor 22 is formed with a groove 25 for selectively connecting any one of the distribution ports <1> to <8> and the common port <0> by rotating.
Then, when the sample liquid or the like passes through the hole 23, the groove 25, and the hole 24 in the valve, the sample liquid comes into contact with the inner surfaces, and heat is taken away by the ceramic block.

Ceramic (alumina) is a material excellent in chemical resistance like PTFE, but not only that, but comparing the thermal conductivity of PTFE (temperature 293K) and ceramic (alumina: temperature 300K), the former is 0. .24, the latter is 36.0, and the ceramic valve is more likely to take heat than the PTFE valve.
Actually, the total nitrogen sample that is a solution of about 70 to 80 ° C. sucked from the reaction tank 2 passes through the ceramic valves 1a and 5a and then enters the glass barrel 11a as shown in the experimental data described later. The inflow temperature at that time becomes 55 ° C. or lower.

  Further, the total nitrogen sample, which is a solution of about 70 to 80 ° C. sucked from the reaction tank 2 by the syringe pump 11 in the total nitrogen / total phosphorus meter, is only about 2 ml, and the total heat capacity of the total nitrogen sample Is small enough. Therefore, when the total nitrogen sample passes through the ceramic valves 1a and 5a, the temperature rise on the valve side is somewhat caused but is not particularly problematic. Even if the suction operation is repeated at actual time intervals in practical use, There is no problem with the accumulation of heat.

(Experimental result)
FIG. 6 is experimental data showing the effect of heat radiation by the ceramic valves 1a and 5a in the total nitrogen / total phosphorus meter 101 shown in FIG.
The horizontal axis is the elapsed time from the start of temperature control, and the vertical axis is the temperature. The upper line in FIG. 6 shows the temperature in the reaction tank (TM1 position), and the lower line shows the syringe pump inflow sample temperature (TM2 position).
By stopping the temperature adjustment when 29.4 minutes have elapsed after the start of the temperature adjustment, the temperature (TM1) in the reaction tank 2 thereafter slowly decreases from the temperature 76 ° C. during the temperature adjustment. In addition, after a temperature check is stopped, a mechanical check is performed for several seconds, and immediately, suction of all nitrogen samples (solution after reaction) by the syringe pump 11 starts.
When the suction starts, all the nitrogen sample passes through the ceramic valve 1a, then passes through the ceramic valve 5a, and then flows into the glass barrel 11a when it reaches the position of the syringe pump 11 (29.7 minutes have elapsed). However, the syringe pump inflow sample temperature (TM2) rises from that time.
While the syringe pump 11 continues to suck all the nitrogen sample, the cooling capacity is gradually lowered as the tubes of the pipes (P3, P4) and the ceramic valves 1a, 5a are gradually warmed. Will rise. Thereafter, when the last total nitrogen sample from the reaction tank 2 passes through the ceramic valve 5a (29.8 minutes have elapsed), the syringe pump inflow sample temperature (TM2) becomes the maximum value, and the temperature at this time (maximum temperature) ) Is 54 ° C. (that is, 55 ° C. or less), it can be seen that sufficient cooling performance is obtained by the ceramic valves 1a and 5a. Therefore, it was confirmed that the ceramic valves 1a and 5a can also function as the cooling device 13 in FIG.

  In addition, as a result of conducting a comparative experiment under the same conditions using a conventional PTFE valve, the maximum value of the syringe pump inflow sample temperature (TM2) was 73 ° C., and almost no cooling performance was obtained.

  As described above, by adopting ceramic (alumina) valves 1a and 5a excellent in chemical resistance and thermal conductivity, the valve itself could be used as a cooling device. In order to improve the cooling performance, an air cooling mechanism, a water cooling mechanism, and a heat radiation fin may be attached to the ceramic valves 1a and 5a.

P1 Online sample introduction pipe P2 Offline sample introduction pipe P3 Piping P4 Piping (Liquid flow path)
DESCRIPTION OF SYMBOLS 1 1st 8 port valve 2 Reaction tank 3 Measurement cell 4 Discharge pump 5 2nd 8 port valve 6 Sodium hydroxide aqueous solution 7 Peroxodisulfate aqueous solution 8 Hydrochloric acid 9 Drain switching valve 10 Sample switching valve 11 Syringe pump 11a Glass barrel ( Glass container)
12 Stirring pump 13 Cooling device

Claims (3)

In an analyzer that heats and reacts an alkaline solution containing a sample in a reaction vessel, collects the solution after the reaction in a glass container that communicates with the reaction vessel through a liquid channel,
An analyzer characterized in that a cooling device for cooling the solution flowing in the liquid channel is provided on the liquid channel. The analyzer is a total nitrogen / total phosphorus meter,
The reaction vessel is a reaction for generating a reaction based on the ultraviolet oxidative decomposition method by irradiating ultraviolet rays while heating the sample liquid, sodium hydroxide aqueous solution and potassium peroxodisulfate aqueous solution while measuring the total nitrogen. A tank,
The glass container is prepared by weighing a sample solution, an aqueous solution of sodium hydroxide and an aqueous solution of potassium peroxodisulfate, injecting the solution into the reaction vessel, and sucking the solution after the reaction in the reaction vessel to obtain an absorbance measurement cell. It is a glass barrel of a syringe pump for feeding into the tube, the glass barrel and the reaction tank are connected, and the cooling device is provided on a pipe serving as the liquid flow path. The analyzer according to claim 1. In the liquid flow path between the reaction layer and the glass container, at least a flow path for introducing a sample, a flow path for introducing an alkaline solution, a flow path connected to the reaction layer, and a solution after the reaction are measured. The analyzer according to claim 1 or 2, wherein a ceramic valve that connects each flow path including the flow paths is provided so that the ceramic valve can also be used as the cooling device.

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