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Glossary
Reference Electrode
Half cell of the electrochemical cell that
supplies a stable voltage that is known,
constant and completely insensitive to the
measurement solution. Changes in voltages
generated from the pH sensor are measured
versus this electrode’s voltage.
Refractive Index
Refractive Index is defined as the ratio of the
speed of light in empty space to the speed of
light in the substance.
Repeatability
Repeatability expresses the precision under
the same operating conditions over a short
interval of time. Repeatability is also termed
intra-assay precision.
Reproducibility
Reproducibility expresses the precision
between laboratories collaborative studies,
(usually applied to standardization of
methodology).
Resistivity
Electrical resistivity (also known as specific
electrical resistance) is a measure indicating
how strongly a material opposes the flow of
electric current. A low resistivity indicates a
material that readily allows the movement of
electrons. The SI unit for electrical resistivity
is the ohmmeter.
RH
Relative humidity is expressed as the ratio of
the quantity of water vapor present in the air
to the quantity at which the air would reach
saturation (100%) at a given temperature.
Robustness
The robustness of an analytical procedure is a
measure of its capacity to remain unaffected
by small, but deliberate variations in method
parameters and provides an indication of its
reliability during normal usage.
rpm
Revolutions per minute.
RS
Reducing Sugars.
RS232
In
telecommunications,
RS-232
(Recommended Standard 232) is traditional
name for a series of standards for serial
binary single-ended data and control signals.
RS485
In
telecommunications,
RS-485
(Recommended Standard 485) is a standard
defining the electrical characteristics of
drivers and receivers for use in balanced
digital multipoint systems. RS-485 can be
used effectively over long distances and in
electrically noisy environments.
S/cm
The siemens (S) unit is named after Werner
von Siemens, the 19th century German
inventor and entrepreneur in the area of
electrical engineering. Previously to the
siemens per meter unit, mho/cm was used
to measure conductivity, where the unit
“mho” is a reciprocal ohm. The “mho” is “ohm”
spelled backwards. Because of the history
of conductivity, μmho/cm and mmho/cm is
commonly translated to μS/cm and mS/cm
because they correspond one-to-one.
The unit of measurement commonly used
is one millionth of a Siemens per centimeter
(micro-Siemens per centimeter or μS/cm).
When
measuring
more
concentrated
solutions, the units are expressed as
milli-Siemens/cm or mS/cm (thousandths
of a Siemens). For ease of expression,
1000 μS/cm are equal to 1 mS/cm.
Salinity
Salinity is a measurement without the unit
corresponding to the weight of dissolved
salts in seawater. Salinity is calculated
from an empirical relationship between the
conductivity and the salinity of a seawater
sample. Oceanographic Tables and Standards
endorsed by UNESCO/SCOR/ICES/IAPSO are
used for the calculation.
Salinity measurements are performed with
no direct temperature correction. The salinity
range is calibrated using a standard seawater
solution.
17
Glossary
17.16
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