Measurements chemical quantities

In the following example, the measured chemical quantities are fixed by four continuous factors age, treatment A, treatment B and analytical error. Treatment B has been applied to only one sample of the class. Age and treatment A produce variations in composition that cannot be interpreted as deviations from the model they are the inner factors. On the other hand, treatment B cannot be identified as an inner factor because of the lack of information, and its effects fall, with the analytical error, in the outer space. Besides, if the effects of treatment B are noticeably greater than those of the analytical error, the B-treated object can be identified as an outlier, as it really is. 

Applications of Optochemical Sensors for Measuring Chemical Quantities. . 867 O. Wolfbeis, G. E. Boisde... 

Applications of Optochemical Sensors for Measuring Chemical Quantities... 

The value of pH is one of the most frequently measured chemical quantities. There are many ways to measure the pH, but most often it is measured by potentiometry. The classical potentiometric tool for pH measurement has been the hydrogen gas electrode. This is not a very convenient tool in an analytical laboratory and has been replaced in this application by more convenient, albeit somewhat less perfect, electrodes—first of all by glass electrodes and occasionally by the quinhydrone electrode or various metal oxide-type electrodes. 

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