Thermo Scientific Orion 310, Инструкция по эксплуатации

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PerpHecT ® Orion 310, 320, 330 Instruction Manual
Chapter XVI
Introduction to Patented digital
LogR pH Measurement for
Orion 330
Obtaining accurate pH values depends on both correct measurement of
standard and sample temperatures and on compensation for any variations
in these temperatures. This thermal compensation has generally been
accomplished either manually (by measuring sample solution with a
thermometer and then dialing in the measured temperature on the meter),
or automatically (by placing a separate temperature probe together with
a pH electrode in the solution).
The temperature of a solution affects pH measurements in two principal
ways:
1. The pH of buffers and samples actually changes slightly with
temperature. For buffers, this change is known and is built into
the PerpHecT series of meters.
2. The slope of the calibration, which the meter uses to convert
millivolt readings to pH, changes with temperature. At 25 ° C,
a 10 degree change in temperature changes the slope by 3.4%.
How important is direct temperature compensation to pH measurement?
To see the effects of temperature, look up your approximate sample
temperature on the left side of
Table 1 . Read across the top to your
approximate pH value. The value shown at the intersection is the error
a 1
° C change in temperature will cause in pH measurement without
compensation. Accurate temperature compensation is essential to accurate
pH measurement.
Introduction to Patented digital LogR pH Measurement for Orion 330