JPH0721487B2 - Fluorine analyzer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for analyzing fluorine in a sample, and more particularly to fluorine isolation by a pyrohydrolysis method and continuous analysis of the fluorine thus isolated. It relates to a device for doing.

Conventional Technology Fluorine is contained in most substances on the earth such as air, water and soil, and humans ingest a certain amount of fluorine throughout their lives through breathing, eating and drinking. Concerning the amount of fluorine intake, the problem caused by excessive intake is regarded as a problem rather than its deficiency. That is, it has long been known that people in high-fluoride areas and workers who work in workplaces where the concentration of fluorine in the environment is high, such as plaque teeth and bone sclerosis due to excessive intake of fluorine.

In diagnosing such chronic poisoning diseases due to fluorine, health management in a high-concentration fluorine environment, and further determining whether or not to add fluorine to the water supply system, it is necessary to accurately grasp the bioburden of fluorine, and Accurate measurements of the surrounding environmental aspects, namely the fluorine content of air, drinking water, and food are required. In addition, the amount of fluorine in biological samples such as blood, urine, hard tissue, and saliva must be easily and accurately measured.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As a fluorine isolation method currently implemented for measuring the amount of fluorine, there are a dry ashing-steam distillation method, a dry ashing-trace diffusion method, an oxygen bomb method, and a pyrohydrolysis method. Law, etc. Of these, the pyrohydrolysis method is structurally unreasonable for the measurement of biological samples and samples with extremely small fluorine content, although its effectiveness has been theoretically confirmed. It was efficient. That is, a large amount of alkali metal is contained in a biological sample, and this reacts with the inner wall of a pyrolysis tube made of quartz glass that is usually employed for monitoring the sample position and the like, and significantly shortens the tube life. Further, in the case of an extremely low fluorine concentration sample, 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 isolating fluorine from a biological sample and a sample containing a small amount of fluorine in a pyrohydrolysis method effectively and reproducibly.

The measurement of the fluorine isolated in the device of the present invention is based on the ion electrode method widely used in recent years,
It should be noted that the usual static method is susceptible to the so-called memory effect and the dissolution of fluorine from the electrode constituent material.

Means for Solving the Problems In order to achieve the above object, the pyrohydrolysis-fluorine isolation apparatus of the present invention is a pyrolysis tube for housing a sample boat, and a portion separated from the inlet of the pyrolysis tube. To 1000
A main heater capable of heating to ˜1100 ° C., an oxygen / steam supply line for supplying an oxygen stream containing water vapor to the pyrolysis tube, a gas discharged from the pyrolysis tube to condense fluorine ions In a fluorine high-temperature vaporization separation apparatus having a coagulation recovery line for recovering an aqueous solution containing, the pyrolysis tube, the inlet part including a sealable inlet end serving as an insertion port of a sample boat and a drain branch pipe, and A main body portion including a portion separated from the inlet portion, and a terminal portion connected to the condensation recovery line, the main body portion is formed of a non-quartz heat-resistant material, and both ends thereof are the quartz glass inlet portion and It is characterized in that it is fitted and connected to the end portion.

As another aspect of the present invention, the oxygen / steam supply line in the above configuration is configured to thermally decompose the oxygen supply end and the impurity organic fluorine in the oxygen gas, and hydrolyze it with a trace amount of water contained in the oxygen gas. An organic fluorine pyrolysis tube for generating hydrogen fluoride, an adsorption column for adsorbing and removing the decomposed hydrogen fluoride, and a steam generator for passing oxygen gas after adsorbing the hydrogen fluoride. It is characterized by being arranged in order.

Action In the fluorine isolation apparatus of the present invention, the pyrolysis tube has a main body made of a non-quartz heat-resistant material such as an alumina tube, and is 1000
Since the sample is heated to a thermal decomposition temperature of ~ 1100 ° C, even if the sample is a biological solution sample such as serum, the reaction between the alkali metal in the sample and the tube material does not occur. Further, the sample is heated to several hundreds of degrees Celsius in the pipe up to the portion corresponding to the main heater, and rapid evaporation does not occur, so that the measured value does not vary. Also, in cases other than solution samples,
This can be introduced directly into the main heater section to eliminate instability of the decomposition reaction caused by rapid heating.

In addition, since a steam generator is inserted in the oxygen / steam supply line, the water temperature inside the steam generator is adjusted so that the distillate speed of the condensed water in the pyrolysis tube can be adjusted to a high or low concentration of fluorine in the sample. It can be varied accordingly and adapted for fluorine measurements.

Practical Example FIG. 1 shows a preferred embodiment of the fluorine isolation apparatus by 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 steam to the pyrolysis tube (1), and a CuO filled tube having an O ₂ gas inlet (3) (4) and CaO
A packed column (5), a flow meter (6), and a water flask (7) as a steam generator are arranged.

The CuO filling pipe (4) is made of a material such as quartz that has heat resistance and does not contain fluorine. The latter half of the pipe is filled with cupric acid (CuO) filling material (8) and the outer circumference corresponding to this CuO filling portion. A quartz tube (4) and a heater (9) for heating CuO (8) to about 850 ° C. As a result, the organic fluorine gas, which is an impurity in the oxygen gas introduced into the quartz tube (4) from the inlet (3), is thermally decomposed, and this is hydrolyzed by the water content also contained in the oxygen gas, It is discharged as hydrogen fluoride, and this hydrogen fluoride is absorbed by lime, that is, a CaO packed column (5), from which oxygen gas having an extremely low fluorine content is taken out. This oxygen gas passes through the flow meter (6) and enters the water flask (7), from which it is sent to the pyrolysis tube (1) together with steam. The water flask (7) is housed in a constant temperature bath (10) including an appropriate heating device.

The pyrolysis tube (1) consists of a quartz glass tube inlet (11), an alumina tube body (12) and a second quartz glass tube end (13), which are in turn airtight. Is maintained and fitted to form a single tubular body. The inlet pipe (11) has an inlet opening closed by a lid (14) holding the end of the oxygen / steam supply line, and a drain branch pipe (15) near the inlet end. A pre-heater (16) is arranged on the outer periphery of the rear end portion of the inlet portion (11), a sub-heater (17) is provided on the upstream side of the outer periphery of the main body (12), and a main heater (18) is provided on the downstream side. ) Is placed. As shown, main heater (18)
The heating range of is larger than that of the sub-heater (11). The sample boat (19) is located in the latter half of the main body tube portion (12), that is, within the heating range of the main heater (18) at the sample thermal decomposition position. Sample boat (19)
The tip of the handle protruding from the rear end is located in the inlet (11) at this boat position, and a magnet (20) for driving the sample boat (19) by an external magnetic field is fixed to this tip. Has been done.

The terminal portion (13) of the pyrolysis tube (1) is filled with a platinum mesh (21) as a hydrolysis catalyst to prevent incomplete decomposition of the sample. The thin tube (22) protruding from the terminal end portion (13) and bent in an L shape and hanging down penetrates the water jacket (23) and opens into the styrene receiving bottle (24). Therefore,
The gas phase that has passed through the platinum mesh (21) is condensed in the thin tube (22), passes through hydrogen fluoride (HF) to become hydrosilicofluoric acid, and is dropped into the receiving bottle (24). The receiving bottle (24) is an electronic balance (2
5) It is possible to monitor the amount of hydrofluoric acid solution placed on the surface and collected by dropping.

Incidentally, (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 embodiment has a total length of about
750 mm, outer diameter of about 20 mm, inner diameter of about 16 mm, of which about 1/3 or more of the length is occupied by an inlet part (11) made of a quartz tube, and the remaining part is a body part made of an alumina tube ( 12) and the end portion (13) made of another quartz tube occupy, but the substantial length of the end portion (13) is such that the thickness of the platinum mesh (21) is allowed. In this case, the sample boat (19) which is introduced into the pyrolysis tube (1) by opening the lid (14) has a portion near the inlet portion (11) in the main body portion (12), as shown by the phantom line at first. That is, it is held at a position corresponding to the sub heater (17). On the other hand, the rear part of the inlet part (11) is heated to about 200 ° C. by the preheater (16), so that dew condensation of water vapor in this part is prevented. This prevents the inconvenience of changing the condensation recovery rate (distillation rate) of the vapor phase after thermal decomposition when a large amount of condensed water is generated at the inlet. The sample boat (19) introduced into the main body is first heated and heated stepwise by the sub-heater (17), for example, at intervals of 2 minutes to 150 ° C., 300 ° C., and further 500 ° C. in the first half. It prevents the sample from evaporating due to the rapid heating to the thermal decomposition temperature so that the measured values will not vary. Such stepwise heating by heating raises the sample to an effective preparatory stage before thermal decomposition even for samples other than the solution. The sub heater (1
The heating according to 7) may be continuous temperature increase or constant temperature. Finally, the sample in the sample boat (19) inserted to the position shown by the solid line in FIGS. 1 and 2 is heated to a temperature of 1000 to 1100 ° C. by the main heater (18) to cause thermal decomposition. Fluorine gas generated by thermal decomposition of the sample is
Immediately hydrolyzed with water vapor to form hydrogen fluoride (HF) (2F ₂ + 2H ₂ O → 4HF + O ₂ ). That is, HF is cooled together with water vapor through the thin tube (23), becomes HF hydrogen liquid, and is collected in the sampling bottle (24). When quartz glass is used in the route, the HF aqueous solution reacts with SiO ₂ which is its component.
Although it becomes SiF ₄ , it cannot be recovered as H ₂ SiF ₆ in an aqueous solution.

Since the main body (12) is made of alumina, even if a large amount of alkali metal (Na, K) is contained in a biological sample,
There is no risk of these alkali metals reacting with the tube material during pyrolysis. In other words, eliminating the shortening of life due to the reaction between alkali metal and tube material (quartz) as in the past,
The life of the pyrolysis tube could be extended.

In the examples, an appropriate amount of a sample having a fluorine content of 10 μg or less is precisely weighed in a sample boat (19), and the pyrolysis tube (1) is
Insert it into the sub-heater (1) of the body (12) first.
I pushed it to the part of 7). Here, it is heated to 300 ° C. for about 0.5 minutes for a solid sample and about 1 minute for a liquid sample such as serum, and then the sample boat (19) is pushed to the main heater (18) portion. It was completely pyrolyzed at a temperature of 1000 ° C. Fluorine in the sample is collected as an aqueous solution of hydrogen fluoride together with the condensed water, and then electronic balance (25)
An appropriate amount was sampled while weighing. The oxygen flow rate is
The temperature of the water flask was 2.0 ° C./min, 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 fluoride ion electrode assembly (3
The front flow path of (0) consists of a buffer line (31) and a carrier line (32) and a mixing coil (33) which reaches the measurement electrode of the electrode assembly (30) from the confluence of the buffer line (31) and the carrier line (32). A plunger pump (34) is arranged on the upstream side of 32), and the pump operation mixes the buffer solution and the carrier solution in the mixing coil (33) at a ratio of 1: 1. An anion exchange resin column (35) is installed in the carrier line (32) on the downstream side of the plunger pump (34).
When the sampling unit (36) is inserted in series and an aqueous solution sample is injected from the sampling unit (36), the sample is supported by the carrier liquid and sent to the mixing coil (33). The electrode structure (30) is a reference electrode composed of a measurement electrode Es composed of a fluoride ion electrode using lanthanum fluoride (LaF ₃ ) as an electrode film and a similar fluoride ion electrode connected to this measurement electrode Es by a salt bridge. The potential of the measurement electrode, which consists of Er and is immersed in a liquid having an appropriate amount of fluorine concentration, is extracted according to the fluorine concentration of the sample liquid with respect to the reference electrode potential immersed in the liquid, and this is measured with an ion meter (37).
The data is recorded in the recorder (38) and integrated by the integrator (39). In this case, the measurement electrode Es is housed in a water tank of about 1.5 in order to prevent an error due to a rapid temperature change.

In the above configuration, by circulating a buffer solution containing an appropriate amount of fluorine in the buffer line (31),
The influence of the memory effect of the ion electrode is reduced, and distilled water containing no fluorine is used as the carrier liquid. The anion exchange resin column (35) in the carrier line (32) adsorbs and removes the fluorine eluted from the fluororesin used as the seal material of the plunger pump (34), and eliminates the influence of the measured value. Thus, the sample solution introduced into the mixing coil (33) is mixed 1: 1 with the buffer solution, and before and after that, there is a 1: 1 mixed phase of the buffer solution and the carrier solution each containing an appropriate amount of fluorine. Since they are in contact with each other, there is also an expectation that the above-mentioned memory effect can be prevented and the diffusion of the sample solution can be reduced, and the sensitivity can be improved accordingly.

Further, in the electrode structure (30), it is generally said that the fluorine ion electrode is also used as the reference electrode Er. The value of the reference potential E ⁰ represented by is a relatively large specific value for the fluorine ion electrode and the conventional reference electrode (Ag / AgCl) other than the fluorine ion electrode, and falls within the measurement range of the measurement value recording recorder. It eliminates the inconvenience of not being present. Therefore, the solution the fluorine concentration of the reference electrode side increases the recorder sensitivity by appropriately adjusting, in a case of measuring a very low concentration of fluorine also possible to set the E ⁰ potential within the allowable range of the recorder Becomes

In the above measuring device, the relationship between the concentration of fluorine 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, 0.1,
When the concentration is changed to 0.5 mgF /, the peak value decreases as the concentration increases, but the electrode response becomes faster and the measurement time required for one sample becomes shorter.

Next, the relationship between the flow velocity and the peak value is as shown in FIG. That is, the peak value decreases as the flow velocity (parameter) increases, and the peak value decreases by 1.8% compared to the peak value at 0.6 ml / min.
The peak value of ml / min is reduced to about 80% and to 68% at 3.0 ml / min. On the other hand, as the flow rate increases, the electrode response becomes faster, and the time required to reach the maximum peak after injection of the standard solution is about 60 seconds at 0.6 ml / min, about 20 seconds at 1.8 ml / min, and 3.0 ml. It was about 10 seconds at / min.

Next, the relationship between the loop capacity of the sample and the peak value is as shown in FIG. In Fig. 6, the peak height increases as the loop volume (parameter) increases to 0.05, 0.1, 0.2 and 0.3 ml, but when it exceeds 0.3 ml, the peak height almost reaches 0.4 and 0.5 ml. Does not increase. It is considered that under this condition, the electrode reaches almost equilibrium potential with a sample volume of 0.3 ml or more.

FIG. 7 shows a recording chart of a standard solution having a concentration of 2.0 to 50.0 μgF / during preparation of a calibration curve. In this case, the peak at the right end is the measurement result of 0.1 μl of 2.0 μg F / standard solution, which is about 0.5 μg from the sensitivity of the peak shape.
It is expected that detection is possible even at an extremely low concentration of F / degree (absolute amount of 0.05 ngF). Furthermore, Figure 8 shows a concentration of 20 μgF.
It is a recording chart for confirming reproducibility at /
This 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, the separation of fluorine, which conventionally takes a long time of several hours to several days, is performed with high accuracy without fear of external contamination in only about 10 minutes. I can do it now.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a preferred embodiment of the fluorine isolation apparatus of the present invention, FIG. 2 is a cross-sectional view showing the constitution of a pyrolysis tube which is a main part of the apparatus of FIG. 1, and FIG. 3 is the present invention. Flow injection-a diagram showing a preferred flow path configuration for carrying out the ion electrode method, FIG. 4 is a graph showing a buffer solution fluorine concentration and a peak value using the above-mentioned measuring device, and FIG. 5 is a flow injection. A graph showing the relationship between the flow velocity and the peak value, Fig. 6 is a graph showing the loop volume and the peak value of the sample, Fig. 7 is a recording chart of the standard solution at the time of preparing the calibration curve, and Fig. 8 is a relatively low same fluorine. 6 is a recording chart showing peak reproducibility in concentration. (1) …… Pyrolysis tube (2) …… Oxygen / steam supply line (4) …… CuO packing tube (5) …… CaO packing column (6) …… Flow meter (7) …… Water flask (16) ) …… Preheater (17) …… Sub heater (18) …… Main heater (30) …… Electrode structure (31) …… Buffer line (32) …… Carrier line (33) …… Mixing coil (34) …… Plunger pump (35) …… Anion exchange resin column (36) …… Sampling unit (37) …… Ion meter

Claims (4)

[Claims] 1. A pyrolysis tube for accommodating a sample boat,
A main heater capable of heating a portion apart from the inlet of the pyrolysis tube to 1000 to 1100 ° C., an oxygen / steam supply line for supplying an oxygen stream containing steam to the pyrolysis tube, and the heat In a fluorine high-temperature vaporization separation device equipped with a coagulation recovery line for condensing gas discharged from a decomposition tube to recover an aqueous solution containing fluorine ions, the thermal decomposition tube can be sealed as an insertion port of a sample boat. An inlet end including a separate inlet end and a drain branch pipe, a main body including a portion distant from the inlet, and a terminal end connected to the condensation recovery line, the main body being formed of a non-quartz heat-resistant material. And both ends thereof are fitted and connected to the inlet and the end made of quartz glass. 2. An oxygen / steam supply line for thermally decomposing an oxygen supply end and impurity organic fluorine in oxygen gas, and hydrolyzing with water contained in oxygen gas to produce hydrogen fluoride. An organic fluorine pyrolysis tube, an adsorption column for adsorbing and removing the hydrogen fluoride produced by decomposition,
The apparatus according to claim 1, wherein the apparatus is configured by sequentially arranging a steam generator for passing oxygen gas after adsorbing hydrogen fluoride. 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 the sample boat moves from the first half of the main body of the pyrolysis tube as the magnet moves. While moving to the back of the main body part, the dimensional relationship between each part of the pyrolysis tube and the handle part of the sample boat is set so that the magnet is maintained in the inlet part, and water vapor is introduced into the inlet part. The apparatus according to claim 1, further comprising a preheater for preventing dew condensation. 4. A sub-heater is provided on the outer periphery of the main part of the pyrolysis tube in the middle of the inlet part and the main heater arrangement part, and while the sample boat is located in this part, hundreds of degrees Celsius to several hundreds of degrees 2. The apparatus according to claim 1, wherein the main heater is provided so as to be heated up to 0 ° C. and provided on the outer periphery of the main part including the latter half of the main body.