eutech-instruments cyberscan ph 110 phmvrs232 meter User Manual

Instruction Manual   

 

CyberScan pH 11 / 110  

 

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The electromotive force generated in the glass electrode varies with the temperature 
of the solution. As a result the response of the pH electrode is subjected to variations 
in temperature. Automatic Temperature Compensation compensates for this 
variance.  

A solution’s temperature dependence varies considerably. Some may show an 
increase in pH while others a decrease for the same temperature variation. This is 
why when you are measuring pH values at a particular temperature, even with a pH 
meter having ATC, you must record the solution’s temperature along with the pH 
value, or the measurement may be meaningless. 

Temperature variation also causes variation in liquid junction potential, asymmetry 
potential, and the pH value of the reference solution. To reduce these factors, it is 
important to ensure that the temperature of the standard calibrating solution and the 
sample solution are the same. 

 

Standard pH buffer solutions are used to calibrate or standardise a pH meter before 
you measure the pH of a sample. They serve as reference standards for the basis of 
comparison between measurements. 

The more common standard buffers are the pH 4.01, pH 7.00 and pH 10.01. The 
others include pH 1.68 and pH 12.45. 

For 1-point calibration, you only need a general pH value. Use a standard buffer of 
pH 7.00 or a standard buffer whose pH value is close to that of the sample. 

2-point calibration is used when you know that the sample is acidic or basic. 

• 

• For acidic sample: use standard buffers of pH 7.00 and pH 4.01 

• 

For basic sample: use standard buffers of pH 7.00 and pH 10.01 

3-point calibration is necessary when the sample’s pH is completely unknown. pH 
7.00, pH 4.01 and pH 10.01 standard buffers should be used.