Glossary - Xylem SL Analytics Lab 865 Operating Manual

Lab 865
Asymmetry
Electromotive force of
an electrode
Junction
ORP voltage
pH value
Potentiometry
Slope
Zero point
Adjusting
AutoRange
Calibration
Measured parameter
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Glossary

pH/ORP
see zero point
The electromotive force U of the combination electrode is the measur-
able electromotive force of an electrode in a solution. It equals the
sum of all the galvanic voltages of the combination electrode. Its
dependency on the pH results in the electrode function, which is char-
acterized by the parameters, slope and zero point.
The junction is a porous body in the housing wall of reference elec-
trodes or electrolyte bridges. It arranges the electrical contact
between two solutions and makes the electrolyte exchange more dif-
ficult. The expression, junction, is also used for ground or junction-
less transitions.
The ORP is caused by oxidizing or reducing substances dissolved in
water if these substances become effective on an electrode surface
(e. g. a gold or platinum surface).
The pH value is a measure of the acidic or basic effect of an aqueous
solution. It corresponds to the negative decadic logarithm of the molal
hydrogen ions activity divided by the unit of the molality. The practical
pH value is the value of a pH measurement.
Name of a measuring technique. The signal (depending on the mea-
sured parameter) of the electrode is the electrical potential. The elec-
trical current remains constant.
The slope of a linear calibration function.
The zero point of a pH combination electrode is the pH value at which
the electromotive force of the pH combination electrode at a specified
temperature is zero. Normally, this is at 25 °C.
General information
To manipulate a measuring system so that the relevant value (e. g. the
displayed value) differs as little as possible from the correct value or
a value that is regarded as correct, or that the difference remains
within the tolerance.
Name of the automatic selection of the measuring range.
Comparing the value from a measuring system (e. g. the displayed
value) to the correct value or a value that is regarded as correct.
Often, this expression is also used when the measuring system is
adjusted at the same time (see adjusting).
The measured parameter is the physical dimension determined by
measuring, e. g. pH, conductivity or D.O. concentration.
Glossary
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