JPH03154862A - Fluorine analyzing apparatus - Google Patents

Abstract

PURPOSE:To allow a rapid and highly accurate analysis by forming the respective three parts of a pyrolysis tube for forming hydrogen fluoride by hydrolysis of required materials and condensing and recovering the hydrogen fluoride. CONSTITUTION:Oxygen contg. steam is supplied by an oxygen steam line 2 to the pyrolysis tube formed of an inlet part 14, a body part 11 and a terminal part 13. The inlet part 14 and the terminal part 13 are formed of a quartz glass material and the body part 11 is formed of an aluminum material, etc., which are non-quartz glass materials. A sample boat 19 is moved to the corresponding positions of a preheater 16, a sub heater 17 and a main heater 18 via a magnet 20 and is successively heated. The sample contg. fluorine in the boat 19 is hydrolyzed and the hydrogen fluoride is formed. Since the body part 11 is formed of the non-quartz glass materials which do not act with the alkaline metal in the sample, the hydrogen fluoride is rapidly and exactly formed and is condensed by a capillary 23. The rapid and highly accurate fluorine analysis is executed by weighing with a balance 25.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an apparatus for analyzing fluorine in a sample, and in particular to an apparatus for isolating fluorine by pyrohydrolysis and continuously analyzing fluorine isolated thereby. This invention relates to a device for analysis.

BACKGROUND OF THE INVENTION Fluorine is contained in most substances on earth, such as air, water, and soil, and humans ingest a certain amount of fluoride throughout their lives through breathing, eating and drinking, etc. Regarding fluoride intake, the harmful effects of excessive intake are viewed as more of a problem than its deficiency. In other words, it has been known for a long time that people living in high-fluoride areas and workers working in workplaces with high concentrations of fluoride in the environment develop mottled teeth and presclerosis due to excessive fluoride intake.

In diagnosing chronic poisoning diseases caused by fluoride, managing health in high-concentration fluoride environments, and deciding whether or not to add fluoride to water supplies, it is first necessary to accurately understand the biological load of fluoride. Accurate measurement of fluorine content in surrounding environmental aspects, such as air, drinking water, and food products, is required. Furthermore, it must be possible to easily and accurately measure the presence of fluorine in biological samples such as blood, urine, hard tissue, and saliva.

Problems to be Solved by the Invention Current fluorine isolation methods for measuring the amount of fluorine include: ■Dry ashing-steam distillation method, ■Dry ashing-microdiffusion method, ■Oxygen pump method, and ■Pyrohydrolysis method, etc. Among these, the pyrohydrolysis method described in (■), although its effectiveness has been theoretically confirmed, is structurally unreasonable for measuring biological samples and samples with minute fluorine content. , it was inefficient. In other words, biological samples contain large amounts of alkali metals, which react with the inner walls of pyrolysis tubes made of quartz glass that are normally used to monitor sample positions, significantly shortening the tube's lifespan.
lower. Furthermore, in the case of extremely low fluorine concentration samples, the measured value changes due to the presence of impurity fluorine in the oxygen gas supplied into the tube.

One object of the present invention is to provide an apparatus for effectively and reproducibly isolating fluorine from biological samples and samples containing trace amounts of fluorine in the pyrohydrolysis method.

The fluorine isolated using the device of the present invention is measured by the ion electrode method, which has been widely used in recent years.
Conventional static methods have problems in that they are susceptible to the so-called memory effect and the dissolution of fluorine from electrode constituent materials. Furthermore, this method is complicated to operate and lacks speed, which ultimately makes it difficult to analyze trace amounts of fluorine.

Therefore, a second object of the present invention is to use ionic electrodes in flow injection systems.

The purpose is to solve the above-mentioned problems caused by the static ion electrode method.

Means for Solving the Problems In order to achieve the above-mentioned first object, the pyrohydrolysis fluorine isolation device of the present invention includes a pyrolysis tube for accommodating a sample port, and a pyrolysis tube for accommodating a sample port. a main heater capable of heating a portion away from the inlet to 1000 to 1100°C; an oxygen/steam supply line for supplying an oxygen stream containing water vapor to the pyrolysis tube; A fluorine high-temperature vaporization separation device equipped with a condensation recovery line for condensing gas and recovering an aqueous solution containing fluorine ions, wherein the pyrolysis tube has a sealable inlet end that serves as an insertion port for a sample boat, and a drain. It consists of the inlet part including the branch pipe, the main body part including the part remote from the inlet part, and the terminal end part connected to the condensation recovery line, the main body part is made of a non-quartz heat-resistant material, and both ends thereof are made of a non-quartz heat-resistant material. It is characterized in that it is fitted and connected to the entrance part and the terminal end part made of quartz glass.

As another aspect of the present invention, the oxygen/steam supply line in the above configuration has an oxygen supply end that thermally decomposes impurity organic fluorine in the oxygen gas and hydrolyzes it by trace moisture contained in the oxygen gas. 1000 to 110 in the fluorinated part
Since the tube is heated to the pyrolysis temperature of 0° C., no reaction occurs between the alkali metal in the sample and the tube material even if the sample is a biological solution sample such as serum. In addition, the sample is heated up to several 100 degrees Celsius in a buffer manner within the tube up to the part corresponding to the main heater, and rapid evaporation does not occur, so there is no variation in measured values. Furthermore, even in cases other than a solution sample, it is possible to directly introduce the sample into the main heater section and eliminate the instability of the decomposition reaction that would occur if it were rapidly heated.

In addition, since a steam generator is inserted in the oxygen/steam supply line, the water temperature in this steam generator is adjusted to adjust the distillate velocity of condensed water in the pyrolysis tube to the level of fluorine concentration in the sample. It can be varied accordingly and adapted to fluorine measurements.

Furthermore, in the fluorine measurement using the 70-injection analysis method of the present invention, the measurement circuit is always closed;
In addition, since a mixture of carrier and buffer solution flows before and after the sample, an organic fluorine thermal decomposition tube is used to generate hydrogen fluoride, and an adsorption column is used to adsorb and remove the hydrogen fluoride produced by the decomposition. , and a steam generator for passing the oxygen gas after the hydrogen fluoride adsorption are sequentially arranged.

Further, a fluorine measuring device configured in accordance with the second object of the present invention is a device that includes a buffer solution supply channel and a sample solution inlet. (5) Consisting of a buffer solution supply channel, a measurement channel that joins the two supply channels to form a mixed flow, and a fluorine ion selective electrode placed in the measurement channel, a measurement electrode housed in the chamber, and a reference electrode in the thermostatic chamber consisting of a similar fluorine ion selective electrode connected to the measurement electrode by a salt bridge; This method is characterized in that the fluorine ion concentration is determined.

Function In the fluorine isolation device of the present invention, the pyrolysis tube eliminates errors caused by the so-called memory effect in the ion electrode of the main body made of a non-quartz heat-resistant material such as an alumina tube, and furthermore, the pyrolysis tube eliminates errors caused by the so-called memory effect. Because it flows in contact with the ion electrode, the solubility of LaF3, which is the electrode membrane material, can be stabilized, resulting in high sensitivity and precision.
Moreover, rapid measurement of fluorine ions becomes possible.

Embodiment FIG. 1 shows a preferred embodiment of a fluorine isolation apparatus using the pyrohydrolysis method of the present invention. (1) is a pyrolysis tube, (2) is an oxygen/steam supply line for supplying an oxygen stream containing water vapor to the pyrolysis tube (1), and is a CuO-filled tube with an 02 gas inlet (3). 4), a CaO packed column (5), a flow meter (6), and a water flask (7) as a steam generator.

The CuO filling tube (4) is made of a heat-resistant, fluorine-free material such as quartz, and the rear half is filled with cupric acid (Cub).
It is filled with a filler (8) and equipped with a heater (9) for heating the quartz tube (4) and Cu0 (8) to about 850° C. on the outer periphery corresponding to the CuO filled portion. As a result, the organic fluorine gas, which is an impurity in the oxygen gas introduced from the inlet (3) into the quartz tube (4), is thermally decomposed, and this is hydrolyzed by the moisture contained in the oxygen gas. The hydrogen fluoride is discharged as hydrogen fluoride, and this hydrogen fluoride is absorbed in a column (5) packed with lime, that is, CaO, from which oxygen gas with an extremely low fluorine content is taken out. This oxygen gas is measured by a flow meter (6)
It passes through and enters the water flask (7), from where it is sent to the pyrolysis tube (1) along with steam. water flask (7)
is housed in a constant temperature oven (1O) containing an appropriate heating device.

The pyrolysis tube (1) has an inlet section (11) made of a quartz glass tube.
It consists of a main body part (12) made of an alumina tube, and a terminal part (13) made of a second quartz glass tube, which are successively fitted while maintaining airtightness to form a tube body. There is. The inlet pipe (11) has an inlet opening sealed by a lid (14) holding the end of the oxygen/steam supply line and has a drain branch pipe (15) adjacent to its inlet end. A preheater (16) is disposed on the outer periphery of the rear end portion of the inlet portion (11), and the main body portion (1
On the outer periphery of 2), there is a sub-heater (17) on the upstream side, and
A main heater (18) is arranged on the downstream side. As shown in the figure, the heating range of the main heater (18) is the same as that of the sub-heater (1
It is larger than the heating range of 1). The sample boat (19) has a main tube part (12) at the sample pyrolysis position.
It is located in the latter half of the main heater (18), that is, within the heating range of the main heater (18). The tip of the handle protruding from the rear end of the sample boat (19) is connected to the inlet (11) at this boat position.
), and this tip part number; is located within the sample boat (19
) for driving by an external magnetic field (20)
is fixed.

The terminal end (13) of the pyrolysis tube (1) is filled with a platinum mesh (21) as a hydrolysis catalyst to prevent incomplete decomposition of the sample. A thin tube (22) protruding from the terminal end (13), bent in an L-shape and hanging down, penetrates the water jacket (23), and the styrene receiver opens into the bottle (24).

Therefore, the gas phase that has passed through the platinum mesh (21) is transferred to the thin tube (2).
2), it condenses into hydrogen fluoride (HF) and becomes hydrofluorosilicic acid, which is then dripped into the bottle (24). The receiver bottle (24) is placed on an electronic balance (25) so that the amount of hydrofluorosilicic acid solution dropped and collected can be monitored.

Note that (26) is an air cooling blower for the pyrolysis tube (1).

The detailed structure of the pyrolysis tube (1) itself is as shown in FIG. In Fig. 2, the pyrolysis tube (1) of the example has a total length of about 750 cm, an outer diameter of about 20 cm, and an inner diameter of 16 m, with an inlet made of a quartz tube over about 1/3 of the length. (11), and the remaining part is occupied by the main body part (12) made of an alumina tube and the end part (13) made of another quartz tube, but the actual length of the end part (13) is Platinum wire mesh (
21). In this case, the lid (1
4) and introduced into the pyrolysis tube (1), the sample boat (19) is first inserted into the main body (12) as shown by the imaginary line.
) is located near the inlet (11), that is, at a position corresponding to the sub-heater (17). On the other hand, the rear part of the inlet part (11) is heated by a preheater (16).
Since it is heated to 0°C, condensation of water vapor in this area is prevented. This is to prevent problems such as a change in the condensation recovery rate (distillation rate) of the gas phase after thermal decomposition due to the generation of a large amount of condensed water at the inlet. Sample boat (19) introduced into the main body
First, in the first half, the sub-heater (17)
For example, 150'C1300℃ at 2 minute intervals, or even 50℃
This is to prevent the sample from evaporating and fluctuating the measured value due to rapid heating to the next pyrolysis temperature by heating the sample in stages to 0''C. ,
Even for samples other than solutions, this method puts the sample in an effective preparation stage before thermal decomposition. In addition, sub heater (17)
The heating may be by continuous temperature increase or constant temperature. Finally, the sample in the sample boat (19) inserted up to the solid line position in FIGS. 1 and 2 is heated to a temperature of 1000 to 1100'C by the main heater (18), causing thermal decomposition. The fluorine gas generated by the thermal decomposition of the sample is immediately hydrolyzed with water vapor and converted into hydrogen fluoride (
HP) (2F+2H20→4HF+O□). That is, HF is cooled together with water vapor through a thin tube (23), becomes an HF aqueous solution, and is collected into a collection unit (24). Note that when quartz glass is used in the path, the HF aqueous solution reacts with its component SiO2 to form SiF4, but there is no alternative to recovering it as H2SiF6 in the aqueous solution.

Since the main body (12) is made of alumina, even if a large amount of alkali metals (Na, K) are contained in a biological sample or the like, there is no fear that these alkali metals will react with the tube material during thermal decomposition. That is, the conventional shortening of the life due to the reaction between the alkali metal and the tube material (quartz) was eliminated, and the life of the pyrolysis tube could be extended.

In the example, an appropriate amount of sample with a fluorine content of 10 μg or less was accurately weighed into a sample boat (19), and the sample was placed in a pyrolysis tube (
1), and first pushed it into the sub-heater (17) of the main body (12). Here, heat to 300°C for about 0.5 minutes for solid samples and about 1 minute for liquid samples such as serum, and then push the sample boat (19) to the main heater (18). So, 1
Complete thermal decomposition treatment was carried out at a temperature of 000°C. Fluorine in the sample was recovered together with condensed water as a hydrogen fluoride aqueous solution, and an appropriate amount was collected while being weighed using an electronic balance (25). Note that the oxygen flow rate was 2.017 minutes, and the temperature of the water flask was 90°C.

FIG. 3 is a diagram showing a preferred flow path configuration of a flow injection-ion electrode system for measuring the fluorine ion concentration of the aqueous solution isolated and extracted as described above. In FIG. 3, this fluorine ion electrode structure (3
The front flow path of 0) consists of a buffer 1 line (31), a carrier line (32), and a mixing coil (33) that reaches the measurement electrode of the electrode assembly (30) from their confluence,
Buffer line (31) and carrier line (32)
) A plunger pump (34) is arranged on the upstream side of
By the pump operation, the buffer solution and carrier solution are mixed in the mixing coil (33) at a ratio of 1:1. An anion exchange resin column (35) and a sampling unit (36) are inserted in series in the carrier line (32) downstream of the plunger pump (34).
When an aqueous solution sample is injected from step 6), this sample is supported by the carrier liquid and sent to the mixing coil (33). The electrode assembly (30) includes a measurement electrode Es consisting of a fluorine ion electrode using lanthanum fluoride (LaF3) as an electrode film, and a reference electrode Er consisting of a similar fluorine ion electrode connected to the measurement electrode ES with a salt bridge. The potential of the measuring electrode corresponding to the fluorine concentration of the sample solution is taken out from the potential of a reference electrode immersed in a solution having an appropriate amount of fluorine concentration, and after this is measured with an ion meter (37), a recorder (38) The signal is recorded at the integrator (39) and integrated by an integrator (39). In this case, the measurement electrode Es is approximately 1.51
It is housed in an aquarium.

In the above configuration, by flowing a buffer solution containing an appropriate amount of fluorine through the buffer line (31), the influence of the memory effect of the ion electrode is reduced, and distilled water, which does not contain any fluorine, is used as the carrier solution. I am using it. The anion exchange resin column (35) in the carrier line (32) adsorbs and removes fluorine eluted from the fluororesin used as a sealing material for the plunger pump (34), thereby eliminating its influence on the measured value.

In this way, the sample solution introduced into the mixing coil (33) is mixed 1:1 with the buffer solution, and a 1:1 mixed phase of a buffer solution and a carrier solution containing an appropriate amount of fluorine is added before and after the sample solution. Since they are in contact with each other, there is an expectation that this will prevent the aforementioned memory effect and also reduce the diffusion of the sample solution, thereby increasing sensitivity.

In addition, in the electrode structure (30), the fact that a fluorine ion electrode is also used for the reference electrode Er means that the value of the reference potential E0, generally expressed as E=E −2,303・RT/F−1ogaF, is and conventional reference electrodes other than fluorine ion electrodes (Ag/AgCj)
This eliminates the inconvenience of having a relatively large unique value within the measurement range of the recorder for recording measured values.
It is something that Therefore, by appropriately adjusting the solution fluorine concentration on the reference electrode side, the sensitivity of the recorder can be increased.
Even when measuring extremely low concentrations of fluorine, it is possible to set the E0 potential within the allowable range of the recorder.

In the above measuring device, the relationship between the fluorine concentration added to the buffer solution (hexamine buffer solution) and the peak value (potential difference) is as shown in FIG. That is, the fluorine concentration (parameter) in the buffer solution is 0.01.0.05.
．． When the concentration is changed to 0.1.0.5 F/l, the peak value decreases as the concentration increases, but the electrode response becomes faster and - the measurement time required for the sample becomes shorter.

Next, the relationship between flow velocity and peak value is as shown in FIG. In other words, the peak value decreases as the flow rate (parameter) increases, and the peak value at 1,8 d/win is about 80% of the peak value at Q, 5 d/sin.
, 3, Ord /win has decreased to about 68%. On the other hand, as the flow rate increases, the response of the electrode becomes faster, and the time required to reach the maximum value of the peak after injecting the standard solution is 0.
, 6 di/win for about 60 seconds, 1.8d/ll1
In, it took about 20 seconds, and at 3°0wl1/a+in, it took about 10 seconds.

Next, the relationship between the loop capacity of the sample and the peak value is as shown in FIG. In Figure 6, the loop capacitance (parameter) is 0.05.0.1.0°2 and 0.3eft.
As the value increases, the peak height also increases, but 0.3
If it exceeds -, the peak height will hardly increase even if it becomes 0.4 and 0.5 -. This is considered to be because under the above conditions, the electrode reaches approximately the equilibrium potential with a sample amount of 0.3- or more.

Figure 7 shows 2,0~50゜0μg during calibration curve creation.
A recording chart of a standard solution with a concentration of F/II is shown. In this case, the rightmost peak is the measurement result of 0.1wi of a standard solution of 2.0μgF/l, and judging from the sensitivity of this peak shape, it is approximately 0.5μgF/1! It is predicted that it can be detected even at extremely low concentrations (absolute amount 0.05 ngF). Furthermore, FIG. 8 is a recording chart for confirming the reproducibility at a concentration of 20 μgF/II, which shows a good result with a coefficient of variation of about 2%.

Effects of the Invention As described above, according to the fluorine isolation device of the present invention, fluorine separation, which conventionally required a long time of several hours to several days, can be carried out in only about 10 minutes with high precision and without the risk of external contamination. I can now do it. Furthermore, the flow injection-ion electrode method used in conjunction with this fluorine isolation method has made it possible to measure concentrations in an extremely practical, rapid, and accurate manner.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing a preferred embodiment of the fluorine isolation device of the present invention, Fig. 2 is a cross-sectional view showing the configuration of a pyrolysis tube which is the main part of the device in Fig. 1, and Fig. 3 is a cross-sectional view showing a preferred embodiment of the fluorine isolation device of the present invention. Figure 4 is a graph showing the buffer solution fluorine concentration and peak value using the above measuring device. Graph showing the relationship between flow rate and peak value. Figure 6 is a graph showing sample loop capacity and peak value. Figure 7 is a record chart of standard solutions used when creating a calibration curve. Figure 8 is a relatively low amount of the same fluorine. It is a recording chart showing peak reproducibility in density. (1)・・・・・・・・・・・・Pyrolysis tube (2)
・・・・・・・・・・・・・・・ Oxygen/steam supply line (4) ・・・・・・・・・・・・ CuO filling pipe (5) ・・・・・・・・・・・・・・・CaO packed column (6)・・・・・・・・・・・・・・・Flow meter (7)・・・・・・・・・・・・・・・water flask (1
6)・・・・・・・・・・・・Preheater (17
)・・・・・・・・・・・・・・・ Sub heater (18)
・・・・・・・・・・・・・・・ Main heater (30)
...... Electrode structure (31)...
・・・・・・・・・・・・Buffer line (32)
・・・・・・・・・・・・・・・Carrier line (3
3)・・・・・・・・・・・・Mixing coil (34)・・・・・・・・・・・・Plunger pump (35)・・・・・・・・・・・・・・・Anion exchange resin column (36)・・・・・・・・・・・・・・・
・Sunfling unit (37)・・・・・・・・・・・・
...Ion Timekeeping Permit Applicant: Daiwa Electronics Industry Co., Ltd. Figure 5

Claims (5)

[Claims] (1) A pyrolysis tube for accommodating a sample boat and a portion of the pyrolysis tube away from the inlet of the pyrolysis tube at 1000 to 1100°C.
an oxygen/steam supply line for supplying an oxygen stream containing water vapor to the pyrolysis tube, and an aqueous solution containing fluorine ions by condensing the gas discharged from the pyrolysis tube. A fluorine high-temperature vaporization separation device equipped with a condensation recovery line for recovering fluorine, wherein the pyrolysis tube has an inlet section including a sealable inlet end that serves as an insertion port for a sample boat, and a drain branch pipe; It consists of a main body part including a part separated from the condensation recovery line, and a terminal part connected to the condensation recovery line, the main body part being made of a non-quartz heat-resistant material, and both ends of which are connected to the inlet part and the terminal part made of quartz glass. A fluorine isolation device characterized by being fitted and connected to. (2) The oxygen/steam supply line has an oxygen supply end and an organic fluorine for thermally decomposing the impurity organic fluorine in the oxygen gas and hydrolyzing it with the moisture contained in the oxygen gas to generate hydrogen fluoride. It is characterized by being constructed by sequentially arranging a pyrolysis tube, an adsorption column for adsorbing and removing the decomposed hydrogen fluoride, and a steam generator for passing the oxygen gas after adsorbing the hydrogen fluoride. 2. The apparatus of claim 1. (3) A magnet driven by an external magnetic field is fixed to the tip of a handle protruding from one end of the sample boat, and as the magnet moves, the sample boat moves from the front half of the main body of the pyrolysis tube to the main body. The dimensional relationship between each part of the pyrolysis tube and the handle of the sample boat is set so that the magnet is maintained within the inlet section while moving to the depths of the sample boat, and water vapor condensation is prevented at the inlet section. 2. Device according to claim 1, characterized in that it is equipped with a preheater for preventing this. (4) A sub-heater is installed on the outer periphery of the main body of the pyrolysis tube, intermediate between the inlet section and the main heater arrangement section, and the temperature ranges from several hundred degrees Celsius to several hundred degrees Celsius while the sample boat is located in this section. 2. The apparatus according to claim 1, wherein the main heater is installed at an outer periphery of a main portion including a rear half of the main body so as to be heated at an elevated temperature. (5) a buffer liquid supply channel, a carrier liquid supply channel with a sample liquid inlet interposed therebetween, a measurement channel for merging the two supply channels to form a mixed flow; a measurement electrode consisting of a fluorine ion-selective electrode arranged in the thermostatic chamber and housed in the thermostatic chamber, and a reference electrode in the constant temperature chamber consisting of a similar fluorine ion-selective electrode connected to the measuring electrode by a salt bridge; A fluorine measuring device comprising: a fluorine ion concentration in a sample is determined from a potential difference between the measuring electrode and the reference electrode.