Thermo Electron CorporationX-4 Orion Star Series Meter
ISE Technique
Preparation of Standards
The standards should be prepared in the same ISE units as required by the sample
results. It is preferable to use serial dilutions with volumetric glassware to obtain
the different concentration levels.
Note: Any reagents such as ionic strength adjustors, should be added to
samples and standards as specified in the electrode User Guide or Instruction
Manual. s
The calibration points should bracket the expected concentration range of the
samples and there should be a tenfold change in concentration (i.e. 1 ppm and
10 ppm or 10 ppm and 100 ppm).
Fresh aliquots of standard should be used at each calibration.
Prior to each day’s measurements, a two or more point calibration should be
performed. To verify the calibration the electrode should be placed in a fresh aliquot
of standard and if the value has changed the electrode should be recalibrated.
Recommended slopes are given with electrode instructions.
It is recommended that the calibration and sample measurements be taken at the
same temperature for greater accuracy and reproducibility.
Note: For greater low-level measurement accuracy, a new low-level ISE
calibration option is available. An additional rinse of the electrode with the
next standard or sample solution is recommended for any low level
measurements. s
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