NORME INTERNATIONALE CEI IEC INTERNATIONAL STANDARD 62021 1 Première édition First edition 2003 06 Liquides isolants – Détermination de l''''acidité – Partie 1 Titrage potentiométrique automatique Insula[.]
Réactifs
Seuls doivent être utilisés des réactifs de qualité analytique reconnue et de l’eau dé-ionisée ou une eau de pureté équivalente.
Réactif titrant
Solution alcoolique d’hydroxyde de potassium à 0,05 mol/l.
Ajouter 3,0 g d’hydroxyde de potassium à 1 000 ml ± 10 ml de 2-propanol Faire bouillir doucement pendant 10 min pour obtenir la solution Refroidir et boucher la fiole.
Allow the solution to sit in a dark place for 2 days, then filter the supernatant liquid through a 5 µm filter membrane Store the filtered liquid in a suitable amber glass bottle.
The concentration of this solution is approximately 0.05 mol/l and should be standardized as described in section 10.1 For periodic testing of equipment in service, a faster titration can be achieved using 0.1 mol/l potassium hydroxide, subject to agreement between the laboratory and the equipment owner, although this may result in lower precision and a reduced detection limit.
Store the solution in a way that protects it from atmospheric carbon dioxide, using a protective tube containing a soda lime absorbent, ensuring it does not come into contact with the stopper, rubber, or grease from the stopcock.
Une solution commerciale alcoolique d'hydroxyde de potassium peut être utilisée, en la diluant si nécessaire à 0,05 mol/l avec du 2-propanol Celle-ci doit être titrée comme décrit en 10.1.
Solvant titrant
Hydrogénophtalate de potassium, étalon primaire
Il convient de le sécher avant utilisation pendant 2 h à 105 °C.
A 0.1 mol/L solution of hydrochloric acid in deionized water, prepared according to ISO 6619, can be utilized Other acids may also be employed, provided they are certified against a primary standard.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
The test sample is dissolved in a solvent and titrated potentiometrically with alcoholic potassium hydroxide, utilizing a glass-indicating electrode alongside a reference electrode The meter readings are automatically plotted against the titrant volumes, with the end-point determined at a pH of 11.5 This method effectively captures all inflection points, demonstrating minimal impact on results from the rapid pH change following the last inflection point.
While use of inflection points is more accurate, it was found that measurement of weak inflection points was more instrument-dependent and gave poorer reproducibility.
Only reagents of recognized analytical grade and de-ionized water or water of equivalent purity shall be used.
Standard volumetric alcoholic solution 0,05 mol/l potassium hydroxide.
Add 3,0 g of potassium hydroxide to 1 000 ml ± 10 ml of 2-propanol Boil gently for 10 min to effect solution Cool and stopper the flask.
Allow the solution to stand in the dark for 2 days and then filter the supernatant liquid through a 5 àm membrane filter Store in a suitable amber glass bottle.
The solution concentration is about 0.05 mol/l and should be standardized as outlined in section 10.1 For routine equipment testing, a quicker titration can be performed using 0.1 mol/l potassium hydroxide, subject to agreement between the laboratory and the equipment owner; however, this may lead to reduced precision and detection limits.
To ensure the solution remains protected from atmospheric carbon dioxide, store it using a guard tube filled with soda-lime absorbent Additionally, avoid any contact with cork, rubber, or saponifiable stopcock grease.
Commercial alcoholic potassium hydroxide solution may be used, if necessary diluting to
0,05 mol/l with 2-propanol This shall be standardized as described in 10.1.
5.4 Potassium hydrogen phthalate, primary standard
This should be dried before use for 2 h at 105 °C.
NOTE A 0,1 mol/l solution of hydrochloric acid in de-ionized water, prepared as in ISO 6619, may be used Other acids may be used, provided they are certified against a primary standard.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
5.5 Electrolyte de référence de chlorure de potassium
Préparer la solution de chlorure de potassium dans l’eau dé-ionisée à la concentration recommandée par le fabricant d’électrode Des solutions commerciales peuvent être utilisées, si elles sont disponibles.
Solutions tampons de pH, adaptées pour l’étalonnage des électrodes, par exemple, pH 4, pH 7 et pH 11.
Peser 8 g de péroxydisulfate d’ammonium dans un bécher en verre Ajouter soigneusement
100 ml d’acide sulfurique à 98 % et agiter doucement Avant utilisation, il convient de laisser reposer la solution toute la nuit pour que le solide se dissolve complètement.
AVERTISSEMENT – Le péroxydisulfate d’ammonium est un agent fortement oxydant L’acide sulfurique est un agent fortement corrosif A manipuler avec précaution.
Des solutions de nettoyage disponibles sur le marché peuvent être utilisées, comme recommandé par le fabricant d’électrodes.
Un titrateur automatique de pH capable de titrer à un point final déterminé par pas variables ou fixes.
The measuring device must be shielded from stray electric fields using a grounding wire to prevent any reading disturbances when any part of the system is touched.
Une burette automatique d’une précision minimale de ±0,005 ml ou plus est exigée.
Un récipient pour la solution de titrage Il doit être équipé d’un tube de protection contenant de la chaux sodée ou d’autres matériaux d’absorption du dioxyde de carbone.
L’utilisation d’une ộlectrode de verre spộcifiquement conỗue pour des titrages en milieu non aqueux est recommandée.
L’électrode doit être raccordée au potentiomètre au moyen d’un câble blindé approprié tel que la résistance entre le blindage et la longueur complète du raccordement électrique soit supérieure à 50 000 MΩ.
The electrode should be made of glass and equipped with a movable joint in the form of a sleeve or cap to facilitate the cleaning of the reference electrolyte container It is advisable to use a double junction electrode filled with potassium chloride electrolyte This electrode is specifically designated for titrations in non-aqueous media.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Prepare a solution of potassium chloride in de-ionized water at the concentration recom- mended by the electrode manufacturer Commercially available solutions may be used where available.
Buffer solutions of suitable pH for calibration of electrodes, for example, pH 4, pH 7 and pH 11.
To prepare the solution, weigh 8 g of ammonium peroxydisulphate and place it in a glass beaker Then, slowly add 100 ml of 98% sulphuric acid while gently stirring Allow the mixture to sit overnight to ensure the solid dissolves completely before use.
WARNING – Ammonium peroxydisulphate is a strong oxidizing agent Sulphuric acid is a strong corrosive agent Handle carefully.
Commercially available cleaning solutions as recommended by the electrode manufacturer may be used.
An automatic pH titrimeter capable of titrating to a fixed end-point using either variable or fixed titrant increments.
The instrument shall be protected from stray electrical fields so that no change of the reading is produced by touching any part of the system with a grounded lead.
An automatic burette with a dispensing accuracy of ±0,005 ml or better is required.
A reservoir for the titrating solution It shall be fitted with a guard tube containing soda lime or other carbon dioxide absorbing material.
A glass electrode specifically designed for non-aqueous titrations is recommended.
To ensure optimal performance, the electrode must be linked to the potentiometer using a properly shielded cable, maintaining a resistance of over 50,000 MΩ between the shielding and the entire length of the electrical connection.
The electrode must be constructed from glass and include a movable joint, such as a sleeve or plug, to enable easy cleaning of the reference electrolyte cell A double junction design is recommended, with the electrolyte cells filled with potassium chloride electrolyte This electrode is specifically intended for non-aqueous titrations.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Certain alternative combinations of electrode-electrolyte have shown satisfactory results, although their corresponding accuracy has not been established Combined electrodes can be utilized as long as they comply with this standard and possess at least a similar response rate.
The stirrer should have variable speed and be equipped with a screw, paddles, or a magnet bar with a chemically inert surface It must be grounded to prevent any reading disturbances during titration.
It is advisable for the container to be as small as possible, just enough to hold the solvent, sample, stirrer, and electrodes, while being inert to the reagents Glass containers are preferred to prevent electrostatic phenomena.
Un dispositif adapté pour le support du bécher, des électrodes, de l’agitateur et de la burette.
Les échantillons doivent être prélevés en suivant la procédure indiquée dans la CEI 60475.
S’assurer que la prise d’essai est représentative en agitant minutieusement, étant donné que tout sédiment présent peut être acide ou avoir absorbé des composés acides de la phase liquide.
8 Préparation et maintenance du système d’électrode
Bien que les électrodes ne soient pas particulièrement fragiles, il convient de les manipuler avec soin à tous moments.
Rincer les électrodes avec le 2-propanol et enfin avec l’eau dé-ionisée.
A la suite de chaque titrage, immerger les électrodes dans l’eau dé-ionisée pour éliminer tout excès d’électrolyte adhérant à l’extérieur de l’électrode et laisser s’écouler l’excès d’eau.
Il convient que le temps d’immersion soit suffisant pour prévenir tout effet de mémoire sur les titrages suivants.
When using the reference electrode, it is essential to remove any potential cap and ensure that the electrolyte level in the electrode is maintained above that of the titration solution to prevent contaminants from entering the electrode.
Nettoyer l’électrode chaque semaine en immergeant la pointe dans de l’acide chlorhydrique
To maintain the electrode's performance, soak it in a 0.1 mol/l cleaning solution for 12 hours, followed by rinsing with deionized water If a more thorough cleaning is required, immerse the electrode tip in the cleaning solution for 5 minutes and then rinse completely with deionized water This cleaning procedure should be performed monthly for regularly used electrodes.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Certain alternative combinations of electrodes and electrolytes have shown promising results, although their precision remains unverified Additionally, combined electrodes can be utilized as long as they meet the standard requirements and exhibit a comparable response speed.
Solutions tampons aqueuses
Solutions tampons de pH, adaptées pour l’étalonnage des électrodes, par exemple, pH 4, pH 7 et pH 11.
Solution de nettoyage
Peser 8 g de péroxydisulfate d’ammonium dans un bécher en verre Ajouter soigneusement
100 ml d’acide sulfurique à 98 % et agiter doucement Avant utilisation, il convient de laisser reposer la solution toute la nuit pour que le solide se dissolve complètement.
AVERTISSEMENT – Le péroxydisulfate d’ammonium est un agent fortement oxydant L’acide sulfurique est un agent fortement corrosif A manipuler avec précaution.
Des solutions de nettoyage disponibles sur le marché peuvent être utilisées, comme recommandé par le fabricant d’électrodes.
Appareillage de titrage potentiométrique
Un titrateur automatique de pH capable de titrer à un point final déterminé par pas variables ou fixes.
The measuring device must be shielded from stray electric fields using a grounding wire to prevent any reading disturbances when any part of the system is touched.
Une burette automatique d’une précision minimale de ±0,005 ml ou plus est exigée.
Un récipient pour la solution de titrage Il doit être équipé d’un tube de protection contenant de la chaux sodée ou d’autres matériaux d’absorption du dioxyde de carbone.
L’utilisation d’une ộlectrode de verre spộcifiquement conỗue pour des titrages en milieu non aqueux est recommandée.
L’électrode doit être raccordée au potentiomètre au moyen d’un câble blindé approprié tel que la résistance entre le blindage et la longueur complète du raccordement électrique soit supérieure à 50 000 MΩ.
The electrode should be made of glass and equipped with a movable joint in the form of a sleeve or cap to facilitate the cleaning of the reference electrolyte container It is advisable to use a double junction electrode filled with potassium chloride-based electrolyte This electrode is specifically intended for titrations in non-aqueous media.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Prepare a solution of potassium chloride in de-ionized water at the concentration recom- mended by the electrode manufacturer Commercially available solutions may be used where available.
Buffer solutions of suitable pH for calibration of electrodes, for example, pH 4, pH 7 and pH 11.
To prepare the solution, weigh 8 g of ammonium peroxydisulphate and place it in a glass beaker Then, slowly add 100 ml of 98% sulphuric acid while gently stirring Allow the mixture to sit overnight to ensure the solid dissolves completely before use.
WARNING – Ammonium peroxydisulphate is a strong oxidizing agent Sulphuric acid is a strong corrosive agent Handle carefully.
Commercially available cleaning solutions as recommended by the electrode manufacturer may be used.
An automatic pH titrimeter capable of titrating to a fixed end-point using either variable or fixed titrant increments.
The instrument shall be protected from stray electrical fields so that no change of the reading is produced by touching any part of the system with a grounded lead.
An automatic burette with a dispensing accuracy of ±0,005 ml or better is required.
A reservoir for the titrating solution It shall be fitted with a guard tube containing soda lime or other carbon dioxide absorbing material.
A glass electrode specifically designed for non-aqueous titrations is recommended.
To ensure optimal performance, the electrode must be linked to the potentiometer using a properly shielded cable, maintaining a resistance of over 50,000 MΩ between the shielding and the entire length of the electrical connection.
The electrode must be constructed from glass and include a movable joint, such as a sleeve or plug, to enable easy cleaning of the reference electrolyte cell A double junction design is advisable, with the electrolyte cells filled with potassium chloride electrolyte This electrode is specifically intended for non-aqueous titrations.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Certain alternative combinations of electrode-electrolyte have shown satisfactory results, although their corresponding accuracy has not been established Combined electrodes can be utilized as long as they comply with this standard and possess at least a similar response rate.
The stirrer should have variable speed and be equipped with a screw, paddles, or a magnet bar with a chemically inert surface It must be grounded to prevent any reading disturbances during titration.
It is advisable for the container to be as small as possible, just enough to hold the solvent, sample, stirrer, and electrodes, while remaining inert to the reagents Glass containers are preferred to prevent electrostatic phenomena.
Un dispositif adapté pour le support du bécher, des électrodes, de l’agitateur et de la burette.
Les échantillons doivent être prélevés en suivant la procédure indiquée dans la CEI 60475.
S’assurer que la prise d’essai est représentative en agitant minutieusement, étant donné que tout sédiment présent peut être acide ou avoir absorbé des composés acides de la phase liquide.
8 Préparation et maintenance du système d’électrode
Bien que les électrodes ne soient pas particulièrement fragiles, il convient de les manipuler avec soin à tous moments.
Rincer les électrodes avec le 2-propanol et enfin avec l’eau dé-ionisée.
A la suite de chaque titrage, immerger les électrodes dans l’eau dé-ionisée pour éliminer tout excès d’électrolyte adhérant à l’extérieur de l’électrode et laisser s’écouler l’excès d’eau.
Il convient que le temps d’immersion soit suffisant pour prévenir tout effet de mémoire sur les titrages suivants.
When using the reference electrode, it is essential to remove any potential cap and ensure that the electrolyte level in the electrode remains above that of the titration solution to prevent contaminants from entering the electrode.
Nettoyer l’électrode chaque semaine en immergeant la pointe dans de l’acide chlorhydrique
To maintain the electrode's performance, it should be soaked in a 0.1 mol/l solution for 12 hours, followed by rinsing with deionized water If a more thorough cleaning is required, immerse the electrode tip in the cleaning solution for 5 minutes, then rinse completely with deionized water This cleaning procedure should be performed monthly for regularly used electrodes.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Certain alternative combinations of electrodes and electrolytes have shown promising results, although their precision remains unverified Additionally, combined electrodes are permissible as long as they meet the standard requirements and exhibit a comparable response speed.
The stirrer must feature variable speed control and be equipped with a propeller, paddle, or magnetic bar made from chemically inert materials Additionally, it should be electrically grounded to ensure accurate meter readings throughout the titration process.
For optimal performance, the vessel should be compact enough to hold the solvent, sample, stirrer, and electrodes while remaining inert to the reagents Glass vessels are recommended to avoid the accumulation of electrostatic charge.
A suitable stand to support the beaker, electrodes, stirrer and burette.
Samples shall be taken following the procedure given in IEC 60475.
Ensure that the test portion is representative by thoroughly mixing, as any sediment present may be acidic or have adsorbed acidic material from the liquid phase.
8 Preparation and maintenance of electrode system
Although electrodes are not particularly fragile they should be handled carefully at all times.
Rinse the electrodes with 2-propanol and finally with de-ionized water.
After each titration, it is essential to rinse the electrodes in de-ionized water to eliminate any excess electrolyte on their surface, ensuring that any residual water is allowed to drain This rinsing process should be thorough enough to prevent memory effects in future titrations.
To ensure optimal performance of the reference electrode, it is essential to remove any plugs during use and maintain the electrolyte level above that of the liquid in the titration vessel This practice helps prevent the entry of contaminants into the electrode.
Agitateur
The stirrer should have variable speed and be equipped with a screw, paddles, or a magnet bar with a chemically inert surface It must be grounded to prevent any reading disturbances during titration.
Récipient de titrage
It is advisable for the container to be as small as possible, just enough to hold the solvent, sample, stirrer, and electrodes, while being inert to the reagents Glass containers are preferred to prevent electrostatic phenomena.
Dispositif de titrage
Un dispositif adapté pour le support du bécher, des électrodes, de l’agitateur et de la burette.
Les échantillons doivent être prélevés en suivant la procédure indiquée dans la CEI 60475.
S’assurer que la prise d’essai est représentative en agitant minutieusement, étant donné que tout sédiment présent peut être acide ou avoir absorbé des composés acides de la phase liquide.
8 Préparation et maintenance du système d’électrode
Bien que les électrodes ne soient pas particulièrement fragiles, il convient de les manipuler avec soin à tous moments.
Rincer les électrodes avec le 2-propanol et enfin avec l’eau dé-ionisée.
A la suite de chaque titrage, immerger les électrodes dans l’eau dé-ionisée pour éliminer tout excès d’électrolyte adhérant à l’extérieur de l’électrode et laisser s’écouler l’excès d’eau.
Il convient que le temps d’immersion soit suffisant pour prévenir tout effet de mémoire sur les titrages suivants.
When using the reference electrode, it is essential to remove any potential cap and ensure that the electrolyte level in the electrode remains above that of the titration solution to prevent contaminants from entering the electrode.
Nettoyer l’électrode chaque semaine en immergeant la pointe dans de l’acide chlorhydrique
For optimal maintenance, soak the electrode in a 0.1 mol/l solution for 12 hours, followed by rinsing with deionized water If a more thorough cleaning is required, immerse the electrode tip in the cleaning solution for 5 minutes, then rinse completely with deionized water This monthly treatment is recommended for regularly used electrodes.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
Certain alternative combinations of electrodes and electrolytes have shown promising results, although their precision remains unverified Additionally, combined electrodes can be utilized as long as they meet the standard requirements and exhibit a comparable response speed.
The stirrer must feature variable speed control and be equipped with a propeller, paddle, or magnetic bar made from chemically inert materials Additionally, it should be electrically grounded to ensure accurate meter readings throughout the titration process.
For optimal performance, the vessel should be compact enough to hold the solvent, sample, stirrer, and electrodes while remaining inert to the reagents Glass vessels are recommended to avoid the accumulation of electrostatic charge.
A suitable stand to support the beaker, electrodes, stirrer and burette.
Samples shall be taken following the procedure given in IEC 60475.
Ensure that the test portion is representative by thoroughly mixing, as any sediment present may be acidic or have adsorbed acidic material from the liquid phase.
8 Preparation and maintenance of electrode system
Although electrodes are not particularly fragile they should be handled carefully at all times.
Rinse the electrodes with 2-propanol and finally with de-ionized water.
After each titration, it is essential to rinse the electrodes in de-ionized water to eliminate any excess electrolyte on their surface, ensuring that any residual water is allowed to drain off This rinsing process should be thorough enough to prevent memory effects in future titrations.
To ensure the integrity of the reference electrode during use, it is essential to remove any plugs and maintain the electrolyte level above that of the liquid in the titration vessel This practice helps prevent the entry of contaminants into the electrode.
To maintain optimal performance, clean the electrode weekly by immersing the tip in 0.1 mol/L hydrochloric acid for 12 hours, then rinse with de-ionized water For more intensive cleaning, soak the electrode tip in a specialized cleaning solution for 5 minutes, followed by a thorough rinse with de-ionized water This comprehensive cleaning process should be performed monthly during regular use.
LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.
When not in use, immerse the lower half of the electrode in deionized water to prevent it from drying out If the electrode does dry, reactivation can be achieved by immersing it in the cleaning solution as described in section 5.7.
It is essential to refill the electrode with potassium chloride-based electrolyte at least once a week When using an electrode with a sleeve, carefully remove the frosted glass sleeve and thoroughly clean both frosted glass surfaces Reattach the sleeve loosely, allowing a few drops of electrolyte to flow out to clean the frosted glass joint and fully wet the frosted surfaces with the electrolyte Finally, replace the sleeve and refill it with potassium chloride-based electrolyte.
When not in use, immerse the electrode in the electrolyte, ensuring that the electrolyte level within the electrode is above the immersion liquid level It is important to cover the filling openings during storage.
The electrode should be properly cleaned at least once a week using a thorough wash with deionized water It is essential to fill it with potassium chloride-based electrolyte (refer to section 5.5).
Daily measurement of the pH value of buffer solutions is essential The titration endpoint corresponding to a pH of 11.5 is then extrapolated and must be entered into the device's software.
Il convient que la linéarité et la pente du titrimètre potentiométrique sur la plage de pH comprise entre 4 et 11 soient conformes aux tolérances du fabricant d’électrodes.
La correction de température doit être appliquée.
Due to the significant impact of temperature on the pH of buffer solutions, it is essential to keep the temperature as close as possible to the calibration temperature specified by the buffer manufacturer.
Installer l’appareillage conformément aux instructions du fabricant.
Rincer et remplir la burette avec la solution alcoolique d’hydroxyde de potassium (voir 5.2) à 0,05 mol/l (ou 0,1 mol/l comme en 5.2).
Titrer la solution alcoolique d’hydroxyde de potassium 0,05 mol/l avec une solution d’hydro- génophtalate de potassium (voir 10.1).