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Glossary
Potentiometric Titration
A Potentiometric Titration can increase
the precision of ISE measurements and
also the number of ionic species that can
be determined. ISEs are commonly used as
indicators for the titrant or sample species
to follow the progress of a precipitation or
complexometric titration. A small change
in reactant addition corresponds to a
large change in electrode potential at its
stoichiometric endpoint. An example of a
precipitation titration is the determination of
chloride using silver nitrate. A silver ISE can be
used to follow this titration. A complexometric
titration is used for the determination of
calcium. A calcium solution is titrated with the
complexing reagent EDTA. During the titration,
there is a gradual decrease in the free Ca
2+
ion
concentrations as more EDTA is added. The
endpoint corresponds to the point when all
the Ca
2+
is complexed. The progress of this
titration can be monitored using a calcium ISE.
Pre-amplified Electrode
Hanna electrode containing an internal pre-
amplifier. The pre-amplifier converts the high
impedance signal from the pH glass to a low
impedance signal thus allowing the user to
use long runs of sensor cable with ordinary
connectors without noisy or voltage drops
resulting in erroneous measurements.
Precision
The precision of an analytical procedure
expresses the closeness of agreement (degree
of scatter) between a series of measurements
obtained from multiple sampling of the same
homogeneous sample under the prescribed
conditions.Precisionmaybeconsideredatthree
levels: repeatability, intermediate precision and
reproducibility.
Precision should be investigated using
homogeneous,
authentic
samples.
However, if it is not possible to obtain
a
homogeneous
sample
it
may
be
investigated
using
artificially
prepared
samples or a sample solution.
The precision of an analytical procedure is
usually expressed as the variance, standard
deviation or coefficient of variation of a series
of measurements.
Intermediate precision expresses within-
laboratories
variations:
different
days,
different analysts, different equipment, etc.
ppb
parts
per
billion;
as
concentration:
1 ppb = 1 μg substance /L solution.
ppm
parts per million; as concentration: 1 ppm =
1 mg substance /L solution; 1%= 10000 ppm.
ppt
parts per thousand; as concentration:
1 ppt = 1 g substance /L solution.
Pt100
Platinum sensors with means a resistance
of 100Ω 0ºC with a temperature coefficient
of 0.00385Ω per degree Celsius. Similar for
Pt1000.
PTFE
PolyTetraFluoroEthylene. Porous PTFE is a
hydrophobic material that is available with
different porosities. Because of its chemical
advantages, PTFE is widely used in industrial
applications.
PVC
Polyvinyl chloride.
PVDF
Polyvinylidene Fluoride—a highly non-reactive
and pure thermoplastic fluoropolymere.
PWT
Pure Water Test.
QC
Quality Control.
Range
The range of an analytical procedure is
the interval between the upper and lower
concentrations of analyte in the sample
(including these concentrations) for which it
has been demonstrated that the analytical
procedure has a suitable level of precision,
accuracy and linearity.
RDT
Resistance Temperature Detectors.
17
Glossary
17.15
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