Hanna-instruments HI 84442 Manuel d'utilisateur télécharger pdf (Page 5)

Potentiometric end point detection using a pH electrode is more objective than using visual end

point determinations with color changing indicators. The HI 84442 minititrator is a potentiometric

titrator. The instrument also can be used as a pH meter. The volume of titrant dispensed necessary

to reach the end point is then used to calculate the water alkalinity expressed in mg/L as CaCO

meq/L as CaCO

Interferences:

• dissolved gases, lost or gained during samples storage or transport can modify the

alkalinity of the samples;

• presence in the samples of the: precipitates, solid suspensions, oils, soaps can coat a pH

electrode;

To eliminate or diminish the interference effects, it is recommended:

• to protect the samples against the atmospheric action (store in an airtight vessel);

• to avoid vigorous shaking or mixing: stir gently;

• maintenance of the pH electrode (see section Electrode Conditioning and Maintenance)

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Hanna-instruments HI 84442 Manuel d'utilisateur Page 5