JP2009265027A - Endotoxin measuring stainless steel instrument - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endotoxin measuring stainless steel instrument capable of suppressing the activity of endotoxin being lost by iron ions eluted from the measuring instrument in a measurement sample containing endotoxin. <P>SOLUTION: An oxide film of a film thickness (≥100 nm) is formed which suppresses iron ions being eluted on the surface of the endotoxin measuring stainless steel instrument. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an endotoxin measuring instrument for detecting endotoxin or measuring its concentration, and particularly relates to an instrument made of stainless steel.

  Endotoxin is a lipopolysaccharide present in the cell wall of Gram-negative bacteria and is the most typical pyrogen. When an infusion solution, injection drug, blood, or the like contaminated with this endotoxin enters the human body, it may cause serious side effects such as fever and shock. For this reason, it is obliged to manage the above drugs so that they are not contaminated by endotoxin.

  By the way, there is a serine protease activated by endotoxin in the blood cell extract of horseshoe crab (hereinafter also referred to as “LAL: Limulus amoebocyte lysate”). When LAL reacts with endotoxin, the coagulogen present in LAL is hydrolyzed into coagulin by the enzyme cascade by serine protease activated according to the amount of endotoxin, and an insoluble gel is associated. Generated. Using this LAL characteristic, endotoxin can be detected with high sensitivity.

  As a method for detecting or measuring the concentration of endotoxin, a sample (hereinafter also referred to as “endotoxin measurement sample”) to be subjected to endotoxin detection or concentration measurement (hereinafter also simply referred to as “endotoxin measurement”). Let the mixture mixed with LAL stand still, invert the container after a certain period of time, determine whether the sample has gelled by the presence or absence of dripping, and whether the sample contains endotoxin above a certain concentration There is a semi-quantitative gelation method. In addition, there are a turbidimetric method for measuring and analyzing the turbidity of a sample accompanying the generation of a gel due to the reaction of LAL and endotoxin over time, and a colorimetric method using a synthetic substrate that develops color by being hydrolyzed by an enzyme cascade.

  Here, when measuring endotoxin by the turbidimetric method, a mixed solution of an endotoxin measurement sample and LAL is generated in a glass measurement cell subjected to dry heat sterilization. Then, the gelation of the mixed solution is optically measured from the outside.

  In the turbidimetric method, it may take a very long time for LAL to gel, particularly in a sample having a low endotoxin concentration. On the other hand, a method capable of measuring endotoxin in a short time is required. By stirring the mixed solution of the endotoxin measurement sample and LAL using, for example, a magnetic stirrer, gel fine particles are generated, and the intensity of the laser light scattered by the gel particles or the intensity of the light transmitted through the mixed liquid is determined. A laser scattering particle measurement method or a stirring turbidimetric method capable of measuring the presence of endotoxin in a sample in a short time has been proposed.

  By the way, it is known that endotoxin is easily affected by iron ions and aluminum ions and easily loses its activity. Unlike the turbidimetric method, the laser scattering particle measuring method and the two methods of stirring turbidimetric method are characterized by stirring the mixed solution of the endotoxin measurement sample and LAL. Therefore, a stainless steel magnetic stirring bar for stirring the endotoxin measurement sample has been a problem as a factor for deactivating endotoxin in the sample.

In particular, when the endotoxin measurement sample does not contain protein or the like, iron ions eluted from the stainless steel magnetic stirrer quickly act on the endotoxin in the sample and deactivate its activity. Regarding endotoxin measurement samples after mixing with LAL, even if iron ions eluted from stainless steel exist, iron ions are overwhelmingly larger than the amount of endotoxins before acting on endotoxins. Iron ions do not reduce endotoxin activity because they are competitively consumed by the proteins contained in a LAL. The influence of iron ions is caused only by contact between the endotoxin of the endotoxin measurement sample before reacting with LAL and a stainless steel magnetic stirrer (instrument).
JP 2004-061314 A JP-A-10-293129 Japanese Patent Laid-Open No. 5-287696

  The objective of this invention is providing the stainless steel instrument for endotoxin measurement which can suppress that the activity of endotoxin is lost by an iron ion in the measurement sample containing endotoxin.

  The present invention for achieving the above object is characterized in that an oxide film having a film thickness capable of suppressing elution of iron ions is formed on the surface of a stainless steel instrument for measuring endotoxin.

  More specifically, it is a stainless steel instrument for measuring endotoxin that is formed of stainless steel and is used for endotoxin detection or concentration measurement, characterized in that an oxide film having a film thickness of 100 nm or more is formed on the instrument surface. To do.

  In other words, in the present invention, the elution of iron ions from the instrument is suppressed by forming an oxide film having a thickness of 100 nm or more on the surface of the instrument for measuring endotoxin formed of stainless steel.

  Here, in stainless steel originally, chromium in the composition is combined with oxygen in the air to form an oxide film, and elution of iron ions is suppressed. However, although it is stainless steel, it is difficult to completely eliminate elution of iron ions. In addition, since endotoxin measurement is a measurement for detecting the presence of a trace amount of endotoxin of pg / mL, it is necessary to suppress elution of iron ions at a very high level.

  Therefore, in endotoxin measuring instruments, more complete countermeasures are required as compared with countermeasures for elution of iron ions in the field of food production and electronic equipment production. On the other hand, the inventors' diligent research has the effect of suppressing iron ion elution that can be used as an instrument for measuring endotoxin by forming an oxide film with a thickness of at least 100 nm on the surface of stainless steel. Has been clarified.

  Therefore, in the present invention, by forming an oxide film having a film thickness of 100 nm or more on the surface of an instrument for measuring endotoxin formed of stainless steel, elution of iron ions from the instrument is suppressed, and an endotoxin measurement sample , It can be suppressed that the endotoxin loses its activity before the measurement.

  In the present invention, the oxide film may have a thickness of 100 nm to 1 μm.

  Here, it has been found that in a stainless steel instrument, when the thickness of the oxide film exceeds 1 μm, the oxide film easily falls off (peels) from the instrument surface. In the endotoxin measurement, as described above, detection of a very small amount of endotoxin is a problem. Therefore, elution of iron ions due to the removal of the oxide film may have a fatal effect on the measurement.

  Therefore, in the present invention, the thickness of the oxide film on the surface of the stainless steel endotoxin measuring instrument is set to 1 μm or less. Thereby, since a more stable oxide film can be formed and maintained on the surface of the instrument, elution of iron ions can be suppressed more reliably.

  Moreover, in this invention, you may form by heat-processing stainless steel or the said instrument at the temperature of 250 to 1000 degreeC. That is, the stainless steel or instrument before instrument formation is heated to a temperature of 250 ° C. or more and 1000 ° C. or less by exposing it to a flame or putting it in a furnace. As a result, a thicker oxide film can be more reliably formed.

  In the present invention, the instrument is a magnetic stirrer that stirs the sample by rolling it with an electromagnetic force that is housed in a predetermined container together with the sample whose endotoxin detection or concentration measurement is to be performed from the outside. There may be.

  The magnetic stirrer for stirring the endotoxin measurement sample needs to be rolled by an external electromagnetic force. Therefore, a material that does not elute iron ions, such as glass or ceramic, cannot be selected as the material for the magnetic stirrer. Further, since the magnetic stirrer collides with the container in which the sample is put by rolling, the oxide film naturally formed on the surface of the magnetic stirrer is easily desorbed or worn out. If it does so, it will be in the situation where an iron ion elutes more easily.

  Therefore, by forming an oxide film having a thickness of 100 nm or more on the magnetic stirrer in the present invention, endotoxin deactivation due to elution of iron ions can be more effectively suppressed.

  In the present invention, the instrument is a magnetic stirrer that stirs the sample by rolling it with an electromagnetic force that is housed in a predetermined container together with the sample whose endotoxin detection or concentration measurement is to be performed from the outside. Yes, it may be formed of JIS standard SUS200 or SUS300 stainless steel, and the oxide film may be formed by heat-treating the magnetic stirrer at a temperature of 250 ° C. or higher and 800 ° C. or lower.

  Here, the magnetic stirrer does not necessarily need to be formed of stainless steel having ferromagnetism. For example, even if a magnetic stirrer is formed using JIS standard SUS200 or SUS300 stainless steel that does not exhibit ferromagnetism, a part of the composition becomes ferromagnetic due to cutting or polishing in the manufacturing stage of the magnetic stirrer. As a result, it can be used as a magnetic stirrer.

  When a magnetic stirrer is formed using such JIS standard SUS200 or SUS300 stainless steel, the crystal structure changes again when heated to a high temperature exceeding 800 ° C. during the formation of the oxide film. It may lose ferromagnetism and become impossible to use as a magnetic stirrer.

Therefore, in the present invention, when an oxide film is formed by heat-treating a magnetic stirrer formed from JIS standard SUS200 or SUS300 stainless steel, the temperature is limited to 800 ° C. or lower. It was. Thereby, elution of iron ions can be suppressed while maintaining the ferromagnetism of a magnetic stirrer formed of JIS standard SUS200 or SUS300 stainless steel.

  In the present invention, the device is an endotoxin measuring device used for detection or concentration measurement of endotoxin by LAL, which is a blood cell extract of horseshoe crab, and detects the endotoxin before being mixed with the LAL. Alternatively, it may be used for a sample whose concentration is to be measured.

  Here, even if iron ions are eluted from the endotoxin measurement sample, if a protein such as LAL is present in the sample, iron ions are consumed by an overwhelming amount of protein compared to the amount of endotoxin. The problem of inactivation of endotoxin does not occur. Therefore, the device according to the present invention can exert its effect particularly effectively when used on an endotoxin sample before being mixed with LAL.

  The means for solving the above-described problems of the present invention can be used in combination as much as possible.

  In the present invention, in endotoxin detection or concentration measurement, endotoxin can be inhibited from reacting with iron ions eluted from the instrument and inactivated, and endotoxin detection or concentration measurement can be performed with higher accuracy. It becomes.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings.

  Stainless steel is an alloy steel mainly containing chromium in order to improve corrosion resistance. It refers to an alloy containing about 10.5% or more of chromium in iron, often including nickel. Stainless steel has the greatest feature that it is not easily rusted, and the elution of iron is generally considered to be very small. That is, in the stainless steel, mainly chromium in its composition is easily and extremely strongly bonded to oxygen in the air or water to form a very stable and thin oxide film, thereby preventing elution of iron. Even if the oxide film layer on the stainless steel surface is damaged due to scratches or the like, it is considered that the oxide film layer is easily regenerated through the above process.

  As a method for positively forming an oxide film layer on the surface of stainless steel, a passivation treatment (passivation) in which a surface treatment is performed with concentrated nitric acid or the like to form a homogeneous oxide film on the stainless steel surface can be exemplified. On the other hand, a member formed of stainless steel can be exposed to a flame or put into a furnace and heated to oxidize the surface of stainless steel with oxygen in the atmosphere to form an oxide film.

  When an oxide film is formed on stainless steel as described above, when the thickness of the oxide film reaches submicron, it is close to the wavelength of light. Therefore, for example, in SUS300 type stainless steel, although depending on the thickness of the oxide film, although the oxide film is originally transparent, the interference of the light reflected by the oxide film and the base metal causes the thickness of the oxide film. It is known that the color changes from yellow → brown → red purple → blue purple → blue. These stainless steel surface treatment methods play a role of texture and rust prevention of members made of stainless steel.

The inventor of the present invention uses various stainless steel processing methods to form an oxide film on the surface of a stainless steel magnetic stirrer (diameter 1 mm, length 5 mm), and samples containing endotoxins are magnetically stirred. After stirring by the pups, it was examined how much endotoxin activity should be inactivated by reacting with LAL. As a result, it was found that the inactivation of endotoxin can be suppressed only when the magnetic stir bar made of stainless steel has a thick oxide film having a film thickness of 100 nm or more.

  Below, the process at the time of forming the oxide film in the magnetic stirring bar of stainless steel in this invention by heat processing and obtaining the colored stainless steel magnetic stirring bar is demonstrated. However, the oxide film forming process according to the present invention is not limited to the process shown below. In addition, the magnetic stirrer which concerns on the following processes is manufactured from the stainless steel which does not show ferromagnetism in addition to the stainless steel which shows ferromagnetism, for example, the SUS200 type | system | group and SUS300 type stainless steel in JIS specification. When the magnetic stirrer is formed of stainless steel that does not exhibit ferromagnetism, it is possible to utilize the fact that part of the composition changes to a ferromagnetic crystal structure by cutting or polishing stainless steel (stainless steel wire) in the machining process. Thus, it can be used as a magnetic stirring bar.

  Here, it was found that when an oxide film is formed on a stainless steel magnetic stir bar by heat treatment, the heating temperature is preferably 250 ° C. or higher and 1000 ° C. or lower, and particularly preferably 300 ° C. or higher and 800 ° C. or lower. Although the reaction time varies greatly depending on the reaction temperature and heating means, it was found that 10 seconds to 3 hours are preferable, and 20 seconds to 2 hours are particularly preferable. Although various heating means are envisaged, flame treatment with an electric furnace or a burner that is easy to control temperature is preferable.

  It also eliminates non-uniformity of the oxide film due to contact between the stainless steel member and the container in which it is placed, contact between the members, and spatial heating non-uniformity of the heating device. For this purpose, the members may be mixed during heating, the heating may be performed a plurality of times, the members may be mixed during the heating, or the position of the members in the heating device may be changed.

  When the magnetic stirrer is made of stainless steel that does not exhibit ferromagnetism (for example, SUS200 series or SUSU300 series), when the heating temperature exceeds 800 ° C., the ferromagnetic crystals formed on the cut surface are rearranged. It turned out that there was a problem that it returned to nonmagnetic and could not be used as a stirrer. Therefore, when the magnetic stirrer is made of stainless steel that does not exhibit ferromagnetism (for example, SUS200 series or SUSU300 series), the heating temperature is preferably 800 ° C. or lower.

  In addition, even when a thicker oxide film is formed by increasing the number of heat treatments, the ferromagnetic crystal is rearranged to return to non-magnetism in a non-ferromagnetic stainless steel material (for example, SUS200 series or SUS300 series). There's a problem. In addition, there is a problem that the film is not held by the base metal and is easily detached and the effect of suppressing elution of iron ions is reduced. The thickness of the oxide film that prevents elution of iron ions without causing such problems is preferably 100 nm or more and 1 μm or less, depending on the treatment method.

  Moreover, when producing | generating an oxide film by heat processing, you may carry out together with pre-treatments, such as performing the nitric acid treatment before managing oxygen concentration in a furnace appropriately, or performing an oxide-film treatment.

  Here, in order to suppress elution of iron ions, it is conceivable to coat the surface with an appropriate resin instead of forming an oxide film on a stainless steel magnetic stirrer. However, in the case of measuring endotoxin, it is assumed that the endotoxin is not attached to the containers and instruments used for the measurement. Therefore, usually, a dry heat sterilization treatment is performed in which containers and instruments are reacted with high heat (250 ° C. or higher) for 2 hours or longer.

In such high-temperature and long-time treatment, modification and carbonization cannot be avoided except for a small part of the resin. Even if a heat-resistant resin is used, part of the resin may liquefy or vaporize and adhere to the container, causing adverse effects or partial deterioration, and iron ions eluting therefrom. There is concern about the possibility. Therefore, in order to perform the surface treatment of the stainless steel instrument as in the present invention, it is most preferable to perform it inorganically.

  In the present embodiment, a magnetic stirrer will be described as an example of a stainless steel instrument. However, the instruments that are the subject of the present invention include a magnetic stirrer, a sterilizable container for temporarily storing and storing a sample containing endotoxin, and those for the purpose of measuring endotoxin in blood and organs. Examples include tweezers, scissors, needles for collecting samples, and trays for storing samples.

<Production example>
Specific examples of the surface treatment of the magnetic stir bar (stainless steel instrument) in the present embodiment will be described below. The following production examples show an example of the surface treatment, and the treatment conditions of the stainless steel instrument according to the present invention are not limited to the following conditions.

(Production Example 1)
The center of the magnetic stir bar made of SUS301 was pinched with stainless tweezers and exposed to the flame of an alcohol lamp. Careful visual inspection was performed and the material was removed from the flame immediately before it reached a bright orange color. This operation was repeated until the reflection color of the member became tan or blue-purple. Thus, a relatively homogeneous oxide film treatment could be performed even by a method in which temperature control and reaction time control were not performed.

(Production Example 2)
Forty magnetic stir bars made of SUS301 material were put in a crucible and heated in a muffle furnace at a reaction temperature of 600 ° C. and a reaction time of 1 hour. After the temperature dropped, the members inside the crucible were mixed well and then heated again under the same conditions. By the reaction, a magnetic stirrer having a reflection color of tan was obtained.

(Production Example 3)
Forty magnetic stir bars made of SUS301 were put in a crucible and heated in a muffle furnace at a reaction temperature of 700 ° C. and a reaction time of 1 hour. After the temperature dropped, the members inside the crucible were mixed well and then heated again under the same conditions. By the reaction, a magnetic stirrer having a bluish purple reflection color could be obtained.

(Production Example 4)
Ten magnetic stir bars made of SUS301 were immersed in 5 mL of 30% nitric acid solution, heated to 70 ° C. in a hot water bath, reacted for 3 hours, and subjected to passivation treatment. Since only an oxide film having a thickness of several nanometers is formed by this treatment, no change was observed in the reflected color.

(Production Example 5)
Forty magnetic stir bars made of SUS420 material were put into a crucible and heated in a muffle furnace at a reaction temperature of 700 ° C. and a reaction time of 1 hour. After the temperature dropped, the members inside the crucible were mixed well and then heated again under the same conditions. By the reaction, a magnetic stirrer with a blue-gray reflection color could be obtained.

  In the above production examples, judging from the reaction temperature, reaction time, and reflection color, the thickness of the formed oxide film is determined in the order of Production Examples 3 and 5, Production Example 1, Production Example 2, and Production Example 4. It is thought that it is getting thinner. Moreover, the film thickness of the oxide film in Production Example 3 is 1 μm or less (several hundred nm). The thickness of the oxide film in Production Example 4 is considered to be several nm as described above.

<Measurement example>
Below, the measurement example which compared the performance as an instrument for endotoxin measurement of the magnetic stirrer (stainless steel instrument) in which the oxide film was formed by the method demonstrated by each said manufacture example is demonstrated.

(Measurement Example 1)
A stainless steel magnetic stirrer that has not been subjected to an oxide film formation treatment is placed in a plurality of glass containers (outer diameter 7 mm, height 50 mm) one by one, and the top opening is covered with aluminum foil. Sterilized by dry heat at 3 ° C. for 3 hours. By this dry heat sterilization treatment, the endotoxin adhering to the glass container or the stainless steel magnetic stirring bar is decomposed and made harmless.

  200 μL of an endotoxin aqueous solution (concentration: 10 pg / mL) was placed in a glass container having a stainless steel magnetic stirrer that was not subjected to an oxide film formation treatment. The sample was collected after being stirred for a predetermined time while being kept at 37 ° C. After the collected sample is mixed with LAL reagent (Limulus Single Test Wako ES-II, manufactured by Wako Pure Chemical Industries, Ltd.), a glass measuring container (containing the above-described stainless steel magnetic stirrer that has not been subjected to the oxide film formation treatment) The same material shape as that of the glass container was transferred to a dry-heat sterilized treatment as described above), and the LAL aggregation measurement method by the laser scattering particle measurement method was performed to determine the endotoxin concentration in the sample.

  Here, in the state where the LAL reagent is present in the sample, even if iron ions are eluted from the stainless steel magnetic stirrer that has not been subjected to the oxide film formation treatment, it is quickly captured by the protein in the LAL. Does not adversely affect endotoxin activity. It was measured how the amount of endotoxin obtained as described above was decreased by the stirring time of the endotoxin aqueous solution (predetermined time described above) before mixing with the LAL reagent. The result is shown in FIG. In this case, as shown in FIG. 1, it can be seen that the endotoxin concentration (endotoxin activity) is significantly reduced by the iron ions eluted from the magnetic stirrer even when stirring for a short time of about 1 minute. Moreover, it turns out that the density | concentration (endotoxin activity) of endotoxin further falls, so that stirring time became long.

(Measurement example 2)
The stainless steel magnetic stirrer obtained in Production Examples 2 to 4 and the stainless steel magnetic stirrer not subjected to the oxide film formation treatment were separately put in a glass container in the same procedure as in Measurement Example 1. Similarly, dry heat sterilization treatment was performed. Next, 200 μL of an endotoxin aqueous solution (concentration: 10 pg / mL) was placed in each glass container, and this sample was stirred for 20 minutes while being kept at 37 ° C., and then the sample was collected. The amount of endotoxin in the collected sample was quantified by the method described in Measurement Example 1. The measurement results are shown in FIG. As shown in FIG. 2, the amount of endotoxin that should be originally obtained is correctly quantified only when the sample is stirred with a stainless steel magnetic stirrer in which a thick oxide film is formed by oxidizing stainless steel in Production Example 3. I was able to.

  In addition, when the sample was stirred with the stainless steel magnetic stirrer subjected to the passivation treatment in Production Example 4, endotoxin could hardly be quantified. It is considered that the thickness of the oxide film is insufficient only by ordinary passivation treatment, and endotoxin is inactivated by the eluted iron ions. In addition, in Production Example 2, when the sample was stirred with a magnetic stirrer having an oxide film having an intermediate film thickness between Production Examples 3 and 4, an intermediate amount of endotoxin in the above two cases was quantified. It was.

(Measurement Example 3)
Ten stainless steel magnetic stirrers obtained in Production Example 3 and 10 stainless steel magnetic stirrers obtained in Production Example 4 were prepared, respectively, and placed in glass containers as in Measurement Example 1. Then, dry heat sterilization treatment was performed under the same conditions. Thereafter, ion exchange water (M
200 μL each of illiQ system (manufactured by Millipore) was added, kept at 37 ° C., and stirred at 1000 rpm for 20 minutes. The sample after stirring was collected, and the concentration of iron ions in the sample was measured by an atomic absorption method (Z-5000, manufactured by Hitachi, Ltd.).

  The results are shown in FIG. As shown in FIG. 3, it can be seen that an oxide film having a film thickness obtained by a normal passivation treatment is insufficient to prevent elution of iron ions, and iron ions are eluted in the sample. In this case, the elution concentration of iron ions was 0.28 mg / mL, but this concentration is significantly excessive with respect to the endotoxin concentration (in this case, about 10 pg / mL). Considering together with the results of Measurement Example 2, the oxide film having a film thickness of several nanometers cannot suppress the elution of iron ions, and the endotoxin in the sample is inactivated by the iron ions eluted in the sample. It is thought that the concentration could not be measured accurately.

  On the other hand, in the oxide film having a sufficiently thick film thickness (several hundred nm) obtained in Production Example 3, elution of iron ions can be sufficiently suppressed, and it can be seen that almost no iron ions are eluted in the sample.

  In the above description, an oxide film having a film thickness of several hundreds of nanometers is formed by heat-treating a stainless steel instrument (magnetic stirrer). However, the method for forming a sufficiently thick oxide film is not limited to this. I can't. For example, by immersing stainless steel in a sulfuric acid-chromic acid solution, a film of metal oxide or metal hydroxide having a film thickness of 100 μm to 300 μm is chemically formed on the surface thereof, so-called color stainless steel manufacturing method. The same effect as that of the present invention is expected.

It is a graph which shows the relationship between the stirring time of the endotoxin aqueous solution by the magnetic stirrer made from stainless steel, and the endotoxin concentration quantified by the subsequent measurement. It is a graph which shows the relationship between the surface treatment method of the magnetic stirring bar made from stainless steel, and the degree of endotoxin inactivation by iron ion elution. It is a graph which shows the relationship between the surface treatment method of a stainless steel magnetic stirring bar, and the elution amount of an iron ion.

Claims (6)

A stainless steel instrument for measuring endotoxin that is formed of stainless steel and is used for endotoxin detection or concentration measurement,
A stainless steel instrument for measuring endotoxin, wherein an oxide film having a film thickness of 100 nm or more is formed on the instrument surface.   2. The stainless steel instrument for measuring endotoxin according to claim 1, wherein the oxide film has a thickness of 100 nm to 1 μm.   The stainless steel instrument for measuring endotoxin according to claim 1 or 2, wherein the oxide film is formed by heat-treating stainless steel or the instrument at a temperature of 250 ° C or higher and 1000 ° C or lower.   The instrument is a magnetic stirrer that is contained in a predetermined container together with a sample whose endotoxin is to be detected or whose concentration is to be measured, and is agitated by rolling by an electromagnetic force exerted from outside. Item 4. A stainless steel instrument for measuring endotoxin according to any one of Items 1 to 3. The instrument is a magnetic stirrer that is contained in a predetermined container together with a sample to be subjected to endotoxin detection or concentration measurement, and is agitated by an electromagnetic force exerted from the outside, and stirs the sample. JIS standard SUS200 series Or formed from SUS300 stainless steel,
The stainless steel instrument for measuring endotoxin according to claim 1 or 2, wherein the oxide film is formed by heat-treating the magnetic stirrer at a temperature of 250 ° C or higher and 800 ° C or lower.   The instrument is an instrument for measuring endotoxin by LAL, which is a blood cell extract of horseshoe crab, and is used for measurement of endotoxin, and a sample to be detected or measured for concentration of endotoxin before being mixed with the LAL. The stainless steel instrument for measuring endotoxin according to any one of claims 1 to 5, wherein the instrument is used.

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