Suntex PC-3110-RS, Руководство по эксплуатации, Страница: 49 / 68

8.3 pH Calibration
The instrument provides multi-point standard buffer solution calibration. You may
decide how many points to calibrate the measurement system.(PC-3110 model is up to
3-point; PC-3110RS is up to 5-point.) The principle is according to “Method of Least
Squares”. Apply linear regression to calibration the electrode’s slope and zero point
(Asy, Offset or Zero point).
When calibrating a electrode, you may calibrate 1 to 3 point by any sequence to
provide linear regression for mV and pH multi-calibration of a electrode, and to show
the electrode’s slope and zero point(Asy, offset or Zero point) at 25
°
C. The electrode’s
slope rate which is actual slope divided by theoretical slope and the sensitivity shows
in percentage in the display. In addition, the display shows the linear regression
determination coefficient, R2, of the electrode and buffer solution to provide you an
estimation of an electrode’s regression suitability. According to different combination
of standard buffers, the TECH, NIST, Any buffer solution calibration modes are
provided.
8.3.1 TECH mode ( up to 3-point calibration)
The electrode is automatically calibrated according to pH value and temperature
of TECH standard buffers (pH4.01, pH7.00, pH10.00). The range of zero point and
slope of the electrode is also determined. If one of them is over the range, the
display shows error message of zero point and slope failure. (See appendix Table 1,
pH/temperature table of TECH standard buffers)
8.3.2 NIST mode
The electrode is automatically calibrated according to pH value and temperature
of NIST standard buffers.( pH1.68, pH4.01, pH6.86, pH9.18, pH 12.45). The range
of zero point and slope of the electrode is also determined. If one of them is over
the range, the display shows error message of zero point and slope failure. (See
appendix Table 2, pH/temperature table of NIST standard buffers)
8.3.3 Any mode
The electrode measures mV value of different standard solutions. According to
theoretic slope and the temperature of standard solutions, the display shows a
approximate pH value. Then, you can calibrate the electrode by freely adjust the pH
value as those of the standard solutions’. There is not a zero point range failure
determination by the instrument but only the slope range determination. If the slope
is over the range, the display shows error message of slope failure.
45