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Calibration of the Instrument for Measurement Analysis
Section 6
The Measured Absorbance is the result absorbance after subtracting the Blank Absorbance.
Methods of Calibration
Two methods of calibration are provided in the Orion 2230XP Silica Analyzer.
SINGLE POINT calibration uses high concentration standard alone, and BASE LINE calibration
uses either very low or zero standards.
The base line calibration is provided to improve accuracy for low level measurements and trace
analysis.
For setting up the calibration method, from the MAIN MENU, follow the sequence:
MAIN MENU ➔ SETUP ➔ CALIBRATION PARAMETERS
Set the MODE for SINGLE POINT or BASE LINE.
For Calibration, from the MAIN MENU, follow the sequence:
MAIN MENU ➔ MEASUREMENT ➔ CALIBRATE ➔ CALIBRATE
STANDARD
Single Point Calibration
For single point calibration, typically the intercept value is zero. Therefore, Concentration =
Slope x Absorbance.
The technician may modify the intercept value.
The analyzer uses a 200 ppb concentration standard solution for calibration. The absorbance of
the standard solution is measured and the slope is calculated and stored upon user's
confirmation.
Base Line Calibration
After calibrating using the single point, improved accuracy around the base or zero point may
be further tuned by executing a base line calibration.
A low concentration solution is used and its absorbance is measured in the instrument. Only the
intercept is recalculated as:
Intercept = Concentration (Low) – [Slope X Absorbance (Low)]. This is used along with the
slope for single point calibration.
2230XP Silica Analyzer
Thermo Scientific Orion
39
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