eutech-instruments fluoride epoxy Manual Do Utilizador

Instruction Manual 

 

Fluoride Electrode

 

 

13

               Cs   = concentration of sample 
                o 
 

   Cs   = fluoride standard concentration (0.1M) 

                x 
               Vt   = volume of titrant added to achieve the endpoint of unknown sample 
 

    Vt   = volume of titrant added to achieve the endpoint in standardization 

                x 
 

    Vf   = volume of sample used in sample titration                              

 

    Vf   = volume of standard used in standardization titration. 

 
A typical titration curve is shown in Figure 2. 

 
 
ELECTRODE CHARACTERISTICS         
 

 
Electrode measurements reproducible to 

±2% can be obtained if the electrode is calibrated every 

hour. Factors such as temperature fluctuations, drift, noise, and variations in illumination limit 
reproducibility. Reproducibility is independent of concentration within the electrode's operating 
range. 
 

 
The hydroxide ion, OH

-1

, is an electrode interference. Anions which make the sample more basic, 

such as CO

3

-2

 or PO

4

-3

 would increase the OH

-1

 interference, but do not interfere with direct 

electrode operation.  Other anions commonly associated with fluoride, such as Cl

-1

, Br

-1

, I

-1

, SO

4

-2

, 

HCO

3

-1

, NO

3

-1

, and acetate, do not interfere with correct electrode operation. Most cations do not 

interfere with the response of the fluoride electrode to fluoride ion.