YSI 2700D, Руководство пользователя

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8-3
IB current (Initial Baseline Current). The initial baseline current is monitored before a sample
or calibration and while stabilizing baseline current upon entering RUN Mode. To successfully
enter RUN Mode, the IB current must be stable and below 6 nA.
PL current (Plateau Current). The minimum acceptable plateau current is 5 nA. The maximum
plateau current is 500 nA. A plateau current larger than this will be printed as a string of
asterisks '*****'.
FB current (Final Baseline Current). The final baseline current is printed for calibrations and
samples. The baseline current is monitored during the buffer flush and compared to the initial
baseline current.
Base shift (Baseline Shift). The final and initial baselines are compared and reported as percent
shift. A negative baseline shift is not uncommon with newly-installed membranes. High
concentration samples may yield positive baseline shifts. An excessive positive shift can be an
indicator of the presence of an interfering substance. The message 'Final baseline error' is
printed when the instrument cannot adequately flush the chamber.
Slope (Slope of the plateau). See Figure 6.3. The slope is reported in nanoamps per minute. A
newly-installed membrane may have an elevated plateau slope. An excessive slope can be an
indicator of the presence of an interfering substance.
End Point is the time from dispensing the sample into the sample chamber until the instrument
reads the probe signal. The default value for most chemistry setups is 30 seconds. The value
that you have selected in Setup is displayed in the report. Note: This is not through-put time,
but rather best thought of as "reaction" time or "probe signal development" time.
Cal shift (Calibration Shift). A calibration result is compared to the previous calibration result
and the percent shift is reported. The default setting is 2%. That is, if the shift is greater than
2%, the 2700 SELECT performs another calibration. Up to 5 successive calibration shifts are
permitted before the 'Unable to calibrate' error is displayed. You may select Cal shift values that
better suit your application. See Section 5.3 for details. Excessive calibration shifts may be
caused by faulty membranes, newly-installed membranes or air in the sample chamber.
Temperature (Sample Chamber Temperature) The sample chamber temperature is measured
during a calibration and a sample. The results of a sample are temperature corrected. The 2700
SELECT works at sample chamber temperatures between 15° and 35°C. The 2700 SELECT
only measures and displays temperatures between 10° and 40°C. If the temperature is outside
this range, a string of asterisks '*****' will be printed.
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