JP2000241386A - Method for detecting constant current polarized voltage and apparatus for measuring karl fischer moisture - Google Patents
Method for detecting constant current polarized voltage and apparatus for measuring karl fischer moistureInfo
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- JP2000241386A JP2000241386A JP11230358A JP23035899A JP2000241386A JP 2000241386 A JP2000241386 A JP 2000241386A JP 11230358 A JP11230358 A JP 11230358A JP 23035899 A JP23035899 A JP 23035899A JP 2000241386 A JP2000241386 A JP 2000241386A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、カールフィッシャ
ー水分測定法において好適に用いられる定電流分極電圧
検出方法及びそれを用いたカールフィッシャー水分測定
装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a constant current polarization voltage suitably used in a Karl Fischer moisture measurement method and a Karl Fischer moisture measurement device using the same.
【０００２】[0002]
【従来の技術】この種のカールフィッシャー（以下、
「ＫＦ」と略す）容量滴定法を用いる水分測定のための
検出手段には、近年に至って、その多くがいわゆる定電
流分極電圧検出法を採用している。すなわち、この定電
流分極電圧検出法においては、検出電極でもある双白金
電極に微小電流を通電することで、その双白金間の電圧
を測定する。そして、この場合、通電する微小電流は直
流でも交流でも印加することができるが、最近は、パル
ス状に通電するようにしている。2. Description of the Related Art This type of Karl Fischer (hereinafter, referred to as "Carl Fischer")
Recently, most of the detection means for measuring water content using the volumetric titration method employs a so-called constant current polarization voltage detection method. That is, in this constant current polarization voltage detection method, a small current is applied to a twin platinum electrode which is also a detection electrode, and a voltage between the twin platinum is measured. In this case, the minute current to be applied can be applied in either a direct current or an alternating current.
【０００３】一方、この定電流分極電圧検出法におい
て、滴定溶剤にクロロホルムを主溶媒にするものを用い
た場合、従来の技術による水分測定装置では、実質上、
多量の試料の測定を行うのが困難なものであった。これ
は、クロロホルム溶剤の液抵抗が高い上に、非極性の多
量の試料が滴定溶剤に入り込むことで液抵抗が更に増大
するため、適切な分極電圧のモニタリングができなかっ
たからである。[0003] On the other hand, in this constant current polarization voltage detection method, when a solvent containing chloroform as a main solvent is used as a titration solvent, the conventional moisture measuring apparatus is substantially
It was difficult to measure a large amount of samples. This is because the liquid resistance of the chloroform solvent is high, and a large amount of non-polar sample enters the titration solvent to further increase the liquid resistance, so that appropriate polarization voltage cannot be monitored.
【０００４】[0004]
【発明が解決しようとする課題】上記ＫＦ容量滴定法に
よる水分測定は、次のようなＫＦ滴定反応を利用したも
のである。The measurement of water content by the above KF volumetric titration method utilizes the following KF titration reaction.
【０００５】[0005]
【数１】Ｉ2 ＋ＳＯ2 ＋Ｈ2 Ｏ＋３ＢＡＳＥ→２ＢＡＳ
Ｅ・ＨＩ＋ＢＡＳＥ・ＳＯ3 ＢＡＳＥ・ＳＯ3 ＋ＣＨ3 ＯＨ→ＢＡＳＥ・ＨＳＯ4 Ｃ
Ｈ3 ただし、 ＢＡＳＥ：アミン化合物## EQU1 ## I 2 + SO 2 + H 2 O + 3 BASE → 2 BASE
E · HI + BASE · SO 3 BASE · SO 3 + CH 3 OH → BASE · HSO 4 C
H 3 However, BASE: Amine compound
【０００６】すなわち、このＫＦ容量滴定法による水分
測定での滴定反応については、選択的に水との反応が進
むため、従来から水分の測定に広く適用されている。こ
の場合、ＫＦ容量滴定法では、ヨウ素を含む溶液を滴定
剤として用いることで測定を行い、電量滴定法では、ヨ
ウ化物イオンを陽極酸化してヨウ素を生成させ、これに
よって前記反応を行わせるようにしており、これらの各
法ともに、その検出には、検出電極により過剰のヨウ素
を検出することで、滴定終点を認識しているのである。That is, the titration reaction in the water measurement by the KF volume titration method has been widely applied to the measurement of water since the reaction with water proceeds selectively. In this case, in the KF volume titration method, measurement is performed by using a solution containing iodine as a titrant, and in the coulometric titration method, iodine ions are anodized to generate iodine, and thereby the reaction is performed. In each of these methods, the end point of the titration is recognized by detecting excess iodine with a detection electrode.
【０００７】また、このときの過剰のヨウ素の検出法と
して、通常では、先に述べたように定電流分極電圧検出
法を用いることにより、容量滴定法の場合、ヨウ素の過
剰状態（終点電位以下の状態）が３０秒間持続された時
点で滴定が終了し、電量滴定法の場合には、僅かなヨウ
素の過剰状態を検出できる終点電位を越えた時点で滴定
終了としている。As a method for detecting excess iodine at this time, usually, the constant current polarization voltage detection method is used as described above, and in the case of the volumetric titration method, the excess state of iodine (below the end point potential) is obtained. Is completed for 30 seconds, and in the case of coulometric titration, the titration is terminated when the potential exceeds a terminal potential at which a slight excess of iodine can be detected.
【０００８】一般に、メタノールを多く含む溶剤を滴定
溶剤に用い、ＫＦ試薬によって滴定すると、従来の検出
法においても何らの問題もなく、たとえどのような試料
が添加されても、ＫＦ試薬が過剰に滴下されれば終点に
到達でき、水分測定を正常に行うことが可能である。In general, when a solvent containing a large amount of methanol is used as a titration solvent and titration is performed with a KF reagent, there is no problem in the conventional detection method, and even if any sample is added, the KF reagent becomes excessive. If dropped, the end point can be reached, and moisture measurement can be performed normally.
【０００９】しかしながら、油類の水分測定の場合に
は、油類がメタノールには溶解しないことから通常はク
ロロホルムを主溶媒とする滴定溶剤中で滴定するが、油
類に関しては一般に水分が少ないために、多量の試料を
滴定溶剤に注入することになる。この場合、クロロホル
ムの含有量が多いために滴定溶剤の液抵抗が大きいので
あるが、試料がより多く添加されることによって、その
液抵抗がますます大きくなり、この状態で、パルス状の
一定の微小電流を印加すると、その見かけ上の分極電圧
は、真の分極電圧に対して液抵抗に起因する分極電圧が
大きく加算されたものとなる。従って、実際上では滴定
終点に到達しているのにもかかわらず、いつまで経って
も滴定終点に到達しないかのような現象を生ずるもので
あった。However, in the case of measuring the water content of oils, titration is usually carried out in a titration solvent containing chloroform as a main solvent because the oils do not dissolve in methanol. Then, a large amount of sample is injected into the titration solvent. In this case, the titration solvent has a high liquid resistance due to the high content of chloroform.However, the more the sample is added, the higher the liquid resistance becomes. When a minute current is applied, the apparent polarization voltage is obtained by greatly adding the polarization voltage caused by the liquid resistance to the true polarization voltage. Therefore, in practice, even though the titration end point has been reached, a phenomenon occurs as if the titration end point was not reached forever.
【００１０】本発明は、このような従来の問題点を解消
するためになされたもので、その目的とするところは、
ＫＦ滴定反応による水分測定の際の定電流分極電圧検出
法において、常に正常な態様での分極電圧の検出ないし
はモニタリングをなし得るようにした定電流分極電圧検
出法を及び該方法を用いたカールフィッシャー水分測定
装置を提供することである。The present invention has been made in order to solve such a conventional problem.
A constant current polarization voltage detection method capable of always detecting or monitoring a polarization voltage in a normal mode in a constant current polarization voltage detection method at the time of moisture measurement by a KF titration reaction, and a Karl Fischer using the method. It is to provide a moisture measuring device.
【００１１】[0011]
【課題を解決するための手段】前記目的を達成するため
に、本発明者らは、上記した問題点を改善すべく、ＫＦ
滴定反応による水分測定の際の定電流分極電圧検出法に
ついて種々の検討を重ねた結果、次のような重大な事実
を見出した。すなわち、溶剤に起因する分極電圧への影
響は、パルス状に電流を印加した場合、この印加直後に
おいて普遍的に大きいものであるということである。Means for Solving the Problems To achieve the above object, the present inventors have developed a KF to improve the above-mentioned problems.
As a result of repeated investigations on the method of detecting the constant current polarization voltage when measuring water content by titration reaction, the following important facts were found. That is, the influence on the polarization voltage due to the solvent is generally large immediately after the application of a pulsed current.
【００１２】このときの検討結果について、次に詳細に
述べる。図１は、定電流分極電圧検出法を用いたカール
フィッシャー水分測定において、時間と分極電圧の関係
を表す模式図である。この場合、パルス状微小電流の印
加サイクルを５００ｍｓとし、実際に電流が印加される
パルス幅を５０ｍｓとしている。The result of the study at this time will be described in detail below. FIG. 1 is a schematic diagram showing the relationship between time and polarization voltage in Karl Fischer moisture measurement using the constant current polarization voltage detection method. In this case, the pulse-like minute current application cycle is set to 500 ms, and the pulse width to which the current is actually applied is set to 50 ms.
【００１３】図１に示す様に、メタノール系溶剤で通常
の試料を測定した場合、検出電極で測定された分極電圧
は、水過剰の状態では徐々に上昇し、かつ印加電流を切
ることで減少する。ここで、ヨウ素を含有したＫＦ試薬
が滴下され、かつ水分が滴定されてくると、分極電圧の
上昇もまた次第に減少し、ＫＦ試薬が過剰になること
で、その分極電圧は非常に低くなる。この場合、市販の
容量法による水分測定装置では、一般的には、分極電圧
をそのままの状態で検出し、分極電圧が所定の値（ＫＦ
試薬が過剰になった時点での値。以下同じ。）になった
時を分析終点とするか、あるいは時間に対する分極電圧
の波形を検出し、その分極電圧の印加サイクル１回分の
積分値（図１の斜線部分の面積）を検出し、積分値が所
定の値を終点にしている。As shown in FIG. 1, when a normal sample is measured with a methanol-based solvent, the polarization voltage measured at the detection electrode gradually increases in a state of excess water, and decreases by cutting off the applied current. I do. Here, when the iodine-containing KF reagent is dropped and the water content is titrated, the increase in the polarization voltage also gradually decreases, and the excess KF reagent causes the polarization voltage to become very low. In this case, a commercially available moisture measuring device using the capacitance method generally detects the polarization voltage as it is, and sets the polarization voltage to a predetermined value (KF
The value at the time of reagent excess. same as below. ) Is determined as the end point of the analysis, or the polarization voltage waveform with respect to time is detected, and the integrated value (area of the hatched portion in FIG. 1) for one application cycle of the polarized voltage is detected. The end point is a predetermined value.
【００１４】一方、油類の水分を測定する場合には、こ
れがメタノールに溶解しないため、クロロホルムを主溶
媒とする溶剤を用いる。ところが、このクロロホルムを
主溶媒にした溶剤中では、先にも述べたように、その液
抵抗が高いことから、真の分極電圧の他に液抵抗による
電圧変化も同時に加算されて検出される。また、これに
試料が添加されると、更にその液抵抗の影響が顕著にな
り、図１から明らかな様に、分極電圧がパルス電流の印
加直後に異常パターンを示すことが分かる。そして、水
分を滴定するためにＫＦ試薬が滴下されることにより、
その分極電圧がいくらかは下がる傾向にあるが、ある値
以下にはならない。この結果、試料中の水分は全てＫＦ
試薬で滴定されているが、終点の電圧（または、分極電
圧の積分値）まで下がらないため、いつまでもＫＦ試薬
が滴定され続けることになるものであった。On the other hand, when measuring the water content of oils, a solvent containing chloroform as a main solvent is used because it is not dissolved in methanol. However, in a solvent containing chloroform as a main solvent, as described above, since the liquid resistance is high, a voltage change due to the liquid resistance is also added and detected simultaneously with the true polarization voltage. Further, when the sample is added thereto, the influence of the liquid resistance becomes more remarkable, and as is apparent from FIG. 1, the polarization voltage shows an abnormal pattern immediately after the application of the pulse current. Then, the KF reagent is dropped to titrate the water,
The polarization voltage tends to fall somewhat, but not below a certain value. As a result, all the water in the sample was KF
Although the titration was performed with the reagent, the KF reagent was continuously titrated forever because the voltage at the end point (or the integral value of the polarization voltage) did not drop.
【００１５】以上のような定電流分極電圧検出法を用い
たＫＦ滴定反応による水分測定での実情に鑑み、本発明
者らは、溶剤に起因する分極電圧への影響を回避すべく
鋭意開発努力を続けた結果、パルス状微小電流の印加直
後における分極電圧を除くようにすれば、真の値に極め
て近い分極電圧を検出できることを見出したもので、こ
れによって本発明を完成するに至った。[0015] In view of the above-described situation of moisture measurement by KF titration reaction using the constant current polarization voltage detection method as described above, the present inventors have made intensive efforts to avoid the influence of the solvent on the polarization voltage. As a result, it has been found that if the polarization voltage immediately after the application of the pulsed minute current is removed, a polarization voltage very close to the true value can be detected, thereby completing the present invention.
【００１６】すなわち、本発明の第１の要旨は、溶液中
での電気化学分析に際して検出電極にパルス状に一定の
微少電流を通電し、各回のパルス電流通電時の分極電圧
を順次検出する定電流分極電圧検出方法において、各回
のパルス電流通電開始時から一定時間（ｔo ）経過後か
ら分極電圧を検出することを特徴とする定電流分極電圧
検出方法に存する。第２の要旨は、カールフィッシャー
水分分析において検出電極にパルス状に一定の微少電流
を通電し、各回のパルス電流通電時の分極電圧を順次検
出する定電流分極電圧検出方法において、各回のパルス
電流通電時の分極電圧（Ｘ）の値より各回のパルス電流
通電開始時から一定時間（ｔo ）経過後の分極電圧（Ｘ
o ）を差し引いた分極電圧差（Ｘ−Ｘo ）を検出するこ
とを特徴とする定電流分極電圧検出方法に存する。That is, a first gist of the present invention is that a constant minute current is applied to a detection electrode in a pulsed manner during electrochemical analysis in a solution, and a polarization voltage is sequentially detected at each application of the pulse current. In the current polarization voltage detection method, the polarization voltage is detected after a lapse of a predetermined time (to) from the start of each pulse current application. The second gist is that, in the Karl Fischer moisture analysis, a constant minute current is applied to the detection electrode in a pulsed manner and the polarization voltage at the time of each pulse current application is sequentially detected. From the value of the polarization voltage (X) at the time of energization, the polarization voltage (X
o) A method of detecting a constant current polarization voltage characterized by detecting a polarization voltage difference (X-Xo) obtained by subtracting o).
【００１７】第３の要旨は、定電流分極電圧検出法を用
いたカールフィッシャー水分測定装置において、反応液
に浸した検出電極に定電流をパルス状に通電する機構
と、通電時の分極電圧（Ｘ）を順次検出する機構と、順
次検出された各回のパルス電流通電時の分極電圧（Ｘ）
の値より各回のパルス電流通電開始時から一定時間（ｔ
o ）経過後の分極電圧（Ｘo ）を差し引いた値（Ｘ−Ｘ
o ）を算出する機構と、分極電圧差（Ｘ−Ｘo ）を用い
て水分測定の終点を決定する機構と、その結果から水分
濃度を算出する機構を有する事を特徴とするカールフィ
ッシャー水分測定装置に存する。The third gist is that in a Karl Fischer moisture measuring apparatus using a constant current polarization voltage detection method, a mechanism for applying a constant current in a pulsed manner to a detection electrode immersed in a reaction solution, and a polarization voltage ( A mechanism for sequentially detecting X), and a sequentially detected polarization voltage (X) at each pulse current application
From the start of each pulse current application (t)
o) The value obtained by subtracting the polarization voltage (Xo) after the passage (X-X
o), a mechanism for determining the end point of moisture measurement using the polarization voltage difference (X-Xo), and a mechanism for calculating the moisture concentration from the results. Exists.
【００１８】[0018]
【発明の実施の形態】以下、本発明に係る定電流分極電
圧検出法及びカールフィッシャー水分測定装置に関し詳
細に説明する。本発明に用いられるカールフィッシャー
（以下、「ＫＦ」と略す）水分測定装置は、例えば図３
に示される。装置は、滴定部と測定表示部からなり、滴
定部は、滴定フラスコとＫＦ試薬滴定装置からなり、測
定表示部は、検出部、データ処理部、及び制御部からな
る。滴定フラスコ中には、ＫＦ反応溶剤が入れられる。
ＫＦ反応溶剤は、通常ＫＦ水分測定に用いられるもので
あれば特に制限無く使用する事が出来るが、クロロホル
ム系等の液抵抗の高い反応溶剤等を使用する場合、特
に、本発明の効果が大きい。例えば、クロロホルムが３
０％以上含有するＫＦ反応溶剤を用いる場合に本発明は
優れた効果を表す。この反応溶剤には検出電極が浸され
ている。検出電極には、微少電流がパルス状に印加され
る。パルス状に通電するとは、図２に示される様に、一
定時間の通電及び一定時間の通電中止を印加サイクルと
し、これを繰り返す事である。印加サイクルは、好まし
くは１００〜３０００ｍｓ、更に好ましくは３００〜７
００ｍｓである。前記検出電極に通電するパルス幅は好
ましくは１０〜１０００ｍｓであり、更に好ましくは１
０〜１００ｍｓである。印加電流は、好ましくは３〜１
００μＡであり、更に好ましくは３〜３０μＡである。
測定試料は、水分測定時に滴定フラスコの試料注入口よ
り注入する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a constant current polarization voltage detecting method and a Karl Fischer moisture measuring apparatus according to the present invention will be described in detail. A Karl Fischer (hereinafter abbreviated as “KF”) moisture measuring device used in the present invention is, for example, shown in FIG.
Is shown in The apparatus includes a titration unit and a measurement display unit. The titration unit includes a titration flask and a KF reagent titrator, and the measurement display unit includes a detection unit, a data processing unit, and a control unit. A KF reaction solvent is placed in the titration flask.
The KF reaction solvent can be used without any particular limitation as long as it is generally used for KF moisture measurement. However, when a reaction solvent having a high liquid resistance such as chloroform is used, the effect of the present invention is particularly large. . For example, chloroform is 3
The present invention exhibits excellent effects when a KF reaction solvent containing 0% or more is used. The detection electrode is immersed in the reaction solvent. A minute current is applied to the detection electrode in a pulsed manner. As shown in FIG. 2, energizing in a pulse shape means energizing for a certain period of time and stopping energizing for a certain period of time, and repeating this. The application cycle is preferably 100 to 3000 ms, more preferably 300 to 7 ms.
00 ms. The pulse width for energizing the detection electrode is preferably 10 to 1000 ms, more preferably 1 to 1000 ms.
0 to 100 ms. The applied current is preferably 3 to 1
00 μA, and more preferably 3 to 30 μA.
The measurement sample is injected from the sample injection port of the titration flask when measuring the moisture.
【００１９】測定試料が滴定フラスコに注入後、ＫＦ試
薬滴定装置から、ヨウ素を含んだＫＦ滴定試薬が滴定フ
ラスコ中に一定間隔で添加される。滴定試薬の１回の添
加量は、制御部により制御され、制御部の信号の伝達に
より、パルスモーターがピストンビュレットを動かし、
これにより、ＫＦ滴定試薬がＫＦ試薬滴定装置より押し
出されて、滴定ノズルより滴下される。滴定フラスコ中
の水分量が多いほど、多くの滴定試薬が添加される。
尚、滴定試薬の添加は、検出電極に電流が印加されてい
ない時に添加される。After the measurement sample is injected into the titration flask, a KF titration reagent containing iodine is added to the titration flask at regular intervals from a KF reagent titrator. The amount of one addition of the titration reagent is controlled by the control unit, and by transmitting a signal from the control unit, the pulse motor moves the piston buret,
Thereby, the KF titration reagent is extruded from the KF reagent titrator and dropped from the titration nozzle. The greater the water content in the titration flask, the more titrant is added.
The titration reagent is added when no current is applied to the detection electrode.
【００２０】図２は、本願発明における検出方法を説明
するための時間と分極電圧の関係を表す模式図である。
検出部には、ＫＦ反応溶剤に浸された検出電極に微少電
流を印加する機構を有し、検出電極の電極間の分極電圧
（Ｘ）を検出する。データ処理部では、順次検出された
各回のパルス電流通電時の分極電圧（Ｘ）の値から各回
のパルス電流の通電開始時から一定時間（ｔｏ）経過後
の分極電圧（Ｘｏ）を差し引いた値（Ｘ−Ｘｏ）を算出
する。通電開始から一定時間（ｔo）経過後とは、パル
ス状の電流を検出電極に印加した直後に発生する分極電
圧の異常な乱れが終了した時間をいう。例えば、図２の
クロロホルム高含有系溶剤を用いて電気絶縁油中の水分
を測定した分極電圧曲線を見ると、電流印加直後、分極
電圧は一端落ち込んでから上昇するが、一定時間（to）
は、分極電圧が上昇を開始して円滑な分極電圧曲線を描
き始めた時間とする。具体的には、通電開始時から一定
時間（ｔo ）とは、測定条件により異なるが、通常は、
０．１〜２００ｍｓ、好ましくは、０．１〜５０ｍｓ、
更に好ましくは、０．１〜５ｍｓである。例えば、滴定
開始前の分極電圧をあらかじめ測定しておき、円滑な分
極電圧曲線を描き始めた時間をｔo として決定し、ＫＦ
分析装置にあらかじめそのｔo の値を記憶させておけば
よい。メタノール系溶媒を用いる場合は、ｔo は任意の
値でよいが、ｔo が大きいと検出される分極電圧差（Ｘ
−Ｘｏ）の値が小さくなるので、精度の面からｔo は小
さい方が好ましい。クロロホルム高含有系溶剤を用いる
のに適当なｔo を分析装置にあらかじめ記憶させておけ
ば、クロロホルム高含有系溶剤を用いる場合も、メタノ
ール系溶媒を用いる場合も、同一装置で精度よく水分測
定ができる。次に分極電圧差（Ｘ−Ｘo ）の積分値を、
通電開始時から一定時間（to）経過後の通電１サイクル
回分ずつ計算する。この積分値は、図２でいえば、分極
電圧波形中の斜線部で表される。この１サイクル分の積
分値の大きさに応じてＫＦ試薬滴定装置からの試薬滴定
量が制御部で制御される。この積分値が、予め設定され
た所定値（ＫＦ滴定試薬が過剰状態での値）になったと
きを分析の終点とし、試薬の滴定がストップされる。こ
の所定値は、予め、ＫＦ過剰状態での値を別途測定して
測定装置にインプットしておく。所定値の定め方として
は、例えば、液抵抗の少ないメタノール系溶剤をＫＦ反
応溶剤として用いてＫＦ滴定試薬が過剰な状態での積分
値を測定して定める。FIG. 2 is a schematic diagram showing the relationship between time and polarization voltage for explaining the detection method in the present invention.
The detection unit has a mechanism for applying a minute current to the detection electrode immersed in the KF reaction solvent, and detects a polarization voltage (X) between the electrodes of the detection electrode. In the data processing unit, a value obtained by subtracting the polarization voltage (Xo) after a lapse of a predetermined time (to) from the start of energization of each pulse current from the value of the polarization voltage (X) at the time of energization of each pulse current detected sequentially. (X-Xo) is calculated. The time after a predetermined time (to) has elapsed from the start of energization refers to the time at which abnormal disturbance of the polarization voltage that occurs immediately after the application of a pulsed current to the detection electrode ends. For example, looking at the polarization voltage curve obtained by measuring the water content in the electrical insulating oil using the chloroform-rich solvent shown in FIG. 2, the polarization voltage immediately drops and then rises for a certain period of time (to).
Is the time when the polarization voltage starts to rise and begins to draw a smooth polarization voltage curve. Specifically, the certain time (to) from the start of energization differs depending on the measurement conditions.
0.1 to 200 ms, preferably 0.1 to 50 ms,
More preferably, it is 0.1 to 5 ms. For example, the polarization voltage before the start of titration is measured in advance, the time at which a smooth polarization voltage curve starts to be drawn is determined as to, and KF is determined.
The value of to may be stored in the analyzer in advance. When a methanol-based solvent is used, to may be an arbitrary value, but the polarization voltage difference (X
−Xo) is small, so that to is preferably small from the viewpoint of accuracy. If the appropriate to value for using the chloroform-rich solvent is stored in the analyzer in advance, the water content can be measured accurately with the same device regardless of whether the chloroform-rich solvent or the methanol solvent is used. . Next, the integral of the polarization voltage difference (X-Xo) is
Calculation is performed for each cycle of energization after a certain time (to) has elapsed from the start of energization. This integral value is represented by a hatched portion in the polarization voltage waveform in FIG. The control unit controls the reagent titer from the KF reagent titrator according to the magnitude of the integrated value for one cycle. When the integrated value reaches a predetermined value (a value when the KF titration reagent is in an excessive state), the analysis is terminated, and the titration of the reagent is stopped. As the predetermined value, a value in an excess KF state is separately measured and input to the measuring device in advance. The predetermined value is determined, for example, by using a methanol solvent having a low liquid resistance as a KF reaction solvent and measuring an integral value in a state where the KF titration reagent is excessive.
【００２１】滴定終了後、データ処理部で使用されたＫ
Ｆ滴定試薬の量から測定試料中の水分量が計算され、ア
ウトプットされる。尚、上記の終点決定法は、分極電圧
差の積分値により決定する方法であるが、分極電圧差
（Ｘ−Ｘo ）が所定の値になった時を終点としても良
い。但し、積分値で決定する方が、分析精度が向上し好
ましい。また、上記は容量滴定法の例を示したが、本発
明は電量滴定法にも用いることが出来、電量滴定法を用
いた分析法、及び、装置も、本発明の趣旨を越えない範
囲で含まれる。After the end of the titration, the K used in the data processing unit
The amount of water in the measurement sample is calculated from the amount of the F titration reagent and output. Although the above-mentioned end point determination method is a method in which the end point is determined by the integral value of the polarization voltage difference, the end point may be set when the polarization voltage difference (X-Xo) reaches a predetermined value. However, determination by the integral value is preferable because the analysis accuracy is improved. Although the above shows an example of the volumetric titration method, the present invention can also be used for the coulometric titration method, and the analysis method and the apparatus using the coulometric titration method are within the scope of the present invention. included.
【００２２】[0022]
【実施例】実験例１ 図３に示したＫＦ水分測定装置を用いて電気絶縁油の水
分を測定した。まず、脱水溶剤ＣＭ（三菱化学( 株) 製
・クロロホルム含有率８７％）５０ｍｌを滴定フラスコ
に入れると共に、ＫＦ試薬ＳＳ（三菱化学( 株) 製）３
ｍｇで前滴定を行い、該滴定フラスコ内を無水化した。
その後、電気絶縁油を約２０ｍｌづつ測定した。検出電
極には、２５μＡの電流を、印加サイクル５００ｍｓ、
電流通電のパルス幅２５ｍｓで印加した。通電時の分極
電圧（Ｘ）を順次検出し、順次検出された通電時の分極
電極（Ｘ）の値より各回のパルス電流通電開始時から１
ｍｓ経過時の分極電圧（Ｘｏ）を差し引いた値（Ｘ−Ｘ
ｏ）を算出した。通電開始時から１ｍｓ経過後の通電１
回分の分極電圧差（Ｘ−Ｘo ）の積分値（図２の斜線部
の面積）が所定の値（ＫＦ試薬が過剰な状態での値）に
なった時を分析の終点とし、電気絶縁油中の水分を計算
した。EXPERIMENTAL EXAMPLE 1 The water content of the electrically insulating oil was measured using the KF water content measuring device shown in FIG. First, 50 ml of a dehydrated solvent CM (manufactured by Mitsubishi Chemical Corporation, chloroform content: 87%) is placed in a titration flask, and KF reagent SS (manufactured by Mitsubishi Chemical Corporation) 3
The titration flask was pre-titrated, and the inside of the titration flask was dehydrated.
Thereafter, about 20 ml of the electric insulating oil was measured at a time. A current of 25 μA is applied to the detection electrode in an application cycle of 500 ms,
The current was applied with a pulse width of 25 ms. The polarization voltage (X) at the time of energization is sequentially detected, and from the value of the sequentially detected polarization electrode (X) at the time of energization, 1 from the start of each pulse current application.
ms minus the polarization voltage (Xo) (XX)
o) was calculated. Energization 1 1 ms after the start of energization
When the integrated value of the polarization voltage difference (X-Xo) of the batch (the area of the hatched portion in FIG. 2) becomes a predetermined value (the value in a state where the KF reagent is excessive), the end point of the analysis is determined. The water content was calculated.
【００２３】比較例１ 分極電圧（Ｘ）を通電開始時からの分極電圧（Ｘ）の通
電１回分の積分値（図１の斜線部の面積）が所定の値
（ＫＦ試薬が過剰な状態での値になった時）を分析の終
点を決定した。それ以外は、実施例１と同様の方法で測
定した。実施例１と比較例１の結果を、表１に示す。COMPARATIVE EXAMPLE 1 The polarization voltage (X) was changed to a predetermined value (the area of the hatched portion in FIG. 1) for one application of the polarization voltage (X) from the start of the application of the polarization voltage (X). Was determined as the end point of the analysis. Otherwise, the measurement was performed in the same manner as in Example 1. Table 1 shows the results of Example 1 and Comparative Example 1.
【００２４】[0024]
【表１】 [Table 1]
【００２５】実験例２ 脱水溶剤ＯＬII（三菱化学( 株) 製・クロロホルム含有
率８２％）５０ｍｌを滴定フラスコに入れると共に、Ｋ
Ｆ試薬ＳＳ−Ｘ（三菱化学( 株) 製）３ｍｇで前滴定を
行い、該滴定フラスコ内を無水化した。その後、灯油を
約１０ｍｌづつ測定した。その他の条件は、実施例１と
同様にして、測定した。Experimental Example 2 50 ml of a dehydrated solvent OLII (manufactured by Mitsubishi Chemical Corporation, chloroform content: 82%) was put into a titration flask, and K
Pretitration was performed with 3 mg of F reagent SS-X (manufactured by Mitsubishi Chemical Corporation), and the inside of the titration flask was dehydrated. Thereafter, about 10 ml of kerosene was measured at a time. Other conditions were measured in the same manner as in Example 1.
【００２６】比較例２ 比較例１に示す従来の終点決定方法を用いた以外は、実
施例２と同様に実施した。実施例２及び比較例２の結果
を表２に示す。Comparative Example 2 An experiment was performed in the same manner as in Example 2 except that the conventional end point determination method shown in Comparative Example 1 was used. Table 2 shows the results of Example 2 and Comparative Example 2.
【００２７】[0027]
【表２】 [Table 2]
【００２８】以上の実験例１，２によって明らかなよう
に、クロロホルムを主溶媒にした溶剤系を用いてもＫＦ
滴定が正常に進行し、これまでは測定不能であった多量
の油試料の正確な水分測定が可能になった。As is clear from the above experimental examples 1 and 2, even when a solvent system using chloroform as a main solvent is used, KF
The titration proceeded normally, and it became possible to accurately measure the water content of a large number of oil samples that could not be measured until now.
【００２９】[0029]
【発明の効果】以上、詳述したように、本発明の定電流
分極電圧検出方法及びこれを用いた装置によれば、溶剤
に起因する分極電圧への影響を有効かつ十分に回避した
分極電圧のモニタリングを行うことができ、これによっ
て正確かつ効果的な水分測定などを実行し得るのであ
る。しかも、本方法自体が極めて簡単であることから、
容易に実施可能であるという優れた特長を有するもので
ある。As described above in detail, according to the method for detecting a constant current polarization voltage and the apparatus using the same according to the present invention, the polarization voltage effectively and sufficiently avoiding the influence of the solvent on the polarization voltage is obtained. Monitoring can be performed, whereby accurate and effective moisture measurement can be performed. Moreover, since the method itself is extremely simple,
It has an excellent feature that it can be easily implemented.
【図１】定電流分極電圧検出法において検出電極に電流
をパルス状に通電した場合の分極電圧曲線の１例を表す
図であって、従来の水分終点検出法によりモニタリング
される積算部を表す図FIG. 1 is a diagram illustrating an example of a polarization voltage curve when a current is applied in a pulsed manner to a detection electrode in a constant current polarization voltage detection method, and illustrates an integrating unit monitored by a conventional moisture end point detection method. Figure
【図２】定電流分極電圧検出法において検出電極に電流
をパルス状に通電した場合の分極電圧曲線の１例を表す
図であって、本発明においてモニタリングされる積算部
を表す図FIG. 2 is a diagram illustrating an example of a polarization voltage curve when a current is applied in a pulsed manner to a detection electrode in the constant current polarization voltage detection method, and illustrates an integration unit monitored in the present invention.
【図３】本発明に用いられるＫＦ分析装置の１例を表す
図FIG. 3 is a diagram showing an example of a KF analyzer used in the present invention.
Claims (8)
極にパルス状に一定の微少電流を通電し、各回のパルス
電流通電時の分極電圧を順次検出する定電流分極電圧検
出方法において、各回のパルス電流通電開始時から一定
時間（ｔo ）経過後から分極電圧を検出することを特徴
とする定電流分極電圧検出方法。In a constant current polarization voltage detection method, a constant minute current is applied in a pulsed manner to a detection electrode during electrochemical analysis in a solution, and a polarization voltage is sequentially detected during each pulse current application. A method of detecting a polarization voltage at a constant current, characterized in that a polarization voltage is detected after a lapse of a predetermined time (to) from the start of pulse current supply.
出電極にパルス状に一定の微少電流を通電し、各回のパ
ルス電流通電時の分極電圧を順次検出する定電流分極電
圧検出方法において、各回のパルス電流通電時の分極電
圧（Ｘ）の値より各回のパルス電流通電開始時から一定
時間（ｔo ）経過後の分極電圧（Ｘo）を差し引いた分
極電圧差（Ｘ−Ｘo ）を検出することを特徴とする定電
流分極電圧検出方法。2. A constant current polarization voltage detection method in which a constant minute current is applied to a detection electrode in a pulsed manner in Karl Fischer moisture analysis and a polarization voltage is sequentially detected during each pulse current application. A polarization voltage difference (X-Xo) obtained by subtracting a polarization voltage (Xo) after a lapse of a predetermined time (to) from the start of each pulse current application from the value of the polarization voltage (X) at the time is detected. Constant current polarization voltage detection method.
ス電流通電開始時から一定時間（ｔo ）経過後の通電１
サイクル分の該分極電圧差（Ｘ−Ｘo ）の積算値が所定
値となった時とする事を特徴とする請求項２記載の定電
流分極電圧検出方法。3. The end point of the measurement of the water analysis is defined as a current 1 after a lapse of a predetermined time (to) from the start of each pulse current application.
3. The constant current polarization voltage detecting method according to claim 2, wherein the integrated value of the polarization voltage difference (X-Xo) for a cycle becomes a predetermined value.
ィッシャー水分測定装置において、反応液に浸した検出
電極に定電流をパルス状に通電する機構と、通電時の分
極電圧（Ｘ）を順次検出する機構と、順次検出された各
回のパルス電流通電時の分極電圧（Ｘ）の値より各回の
パルス電流通電開始時から一定時間（ｔo ）経過後の分
極電圧（Ｘo ）を差し引いた値（Ｘ−Ｘo ）を算出する
機構と、分極電圧差（Ｘ−Ｘｏ）を用いて水分測定の終
点を決定する機構と、その結果から水分濃度を算出する
機構を有する事を特徴とするカールフィッシャー水分測
定装置。4. In a Karl Fischer moisture meter using a constant current polarization voltage detection method, a mechanism for applying a constant current in a pulsed manner to a detection electrode immersed in a reaction solution, and a polarization voltage (X) during energization are sequentially determined. The detection mechanism and the value obtained by subtracting the polarization voltage (Xo) after a lapse of a predetermined time (to) from the start of each pulse current application from the sequentially detected value of the polarization voltage (X) at the time of each pulse current application ( X-Xo), a mechanism for determining the end point of water measurement using the polarization voltage difference (X-Xo), and a mechanism for calculating the water concentration from the results. measuring device.
通電開始時から一定時間（ｔo ）経過後の通電１サイク
ル分の該分極電圧差（Ｘ−Ｘo ）の積算値が所定値とな
った時とする事を特徴とする請求項４記載のカールフィ
ッシャー水分測定装置。5. The end point of the moisture measurement is determined by setting the integrated value of the polarization voltage difference (X-Xo) for one cycle of energization after a lapse of a predetermined time (to) from the start of energization of each pulse current to a predetermined value. 5. The Karl Fischer moisture measurement device according to claim 4, wherein the measurement is carried out at a time when the moisture is measured.
ｍｓであることを特徴とする請求項４又は５記載のカー
ルフィッシャー水分測定装置。6. The fixed time (to) is 0.1 to 200.
6. The Karl Fischer moisture measurement device according to claim 4, wherein the measurement is in milliseconds.
求項４〜６のいずれかに記載のカールフィッシャー水分
測定装置。7. The Karl Fischer moisture measuring apparatus according to claim 4, wherein a volume titration method is used.
求項４〜６のいずれかに記載のカールフィッシャー水分
測定装置。8. The Karl Fischer moisture measuring apparatus according to claim 4, wherein coulometric titration is used.
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