6
|
Calibration of the Instrument for Measurement Analysis
34
|
Orion 2295 Phosphate Analyzer
Thermo Scientific
Section
Section
Theory of Measurement
Measurement in the Orion 2295 Phosphate Analyzer is done by measuring the absorbance of a
single wavelength of light through the sample, and comparing the result with the absorbance of
the same wavelength of light through a standard solution of known concentration. If the two
absorbencies match, then the sample concentration is equal to the standard solution.
To facilitate the comparison, the analyzer is first calibrated with standards to determine the slope
and intercept of the range of concentration it can analyze, and then the measurement of the
unknown sample is interpolated along the calibration curve to calculate the unknown
concentration.
i.e., Concentration = (Slope x Absorbance) + intercept. Where Slope and Intercept - Determined
from Calibration. Absorbance - Calculated through measurement.
The two variables (Slope and Intercept) are available for editing in the calibration parameters
menu screen.
Mode of Measurement
The Orion 2295 Phosphate Analyzer is designed to provide on-line process measurements, and
has two modes of operation. The mode is always displayed at the bottom right, i.e., below the
Info field and above the status field of the display.
The two modes of the instrument are AUTO restart mode (the instrument resumes auto analysis
mode after 0.5 Hr of inactivity) and MANUAL restart mode. The instrument awaits the user to
initiate the RUN or AUTO ANALYSIS mode by pressing the RUN key.
To change the instrument mode, from MAIN MENU follow the sequence:
MENU
➔
SETUP
➔
(+) ANALYSIS PARAMETERS
➔
MODE