Test
Procedures
OQ/PQ Operating Instructions
M1393R0
Page 29 of 60
4.6.2
Theory of the Noise and Drift Calculation of CHROMELEON
CHROMELEON calculates the results of the Noise and Drift test as follows:
•
Signal Noise
– All data points recorded during a 60 seconds segment of a
chromatogram form the basis for determining the noise value. CHROMELEON
calculates a regression line using the method of least squares, then determines the
maximum distance of two data points above and below the line. (When calculating the
regression line, all data points are weighted with their corresponding step unless the
step is equidistant.) Adding both values supplies the noise value. The noise intensity
read in the report is the average noise calculated using 20 segments.
•
Drift
- To compute the drift, a regression line is drawn through all data points. The
slope of the regression line is the calculated drift. Therefore, to compute the drift,
always select a baseline range in which no peaks occur.
4.6.3
Oven accuracy
The temperature in the Ultimate oven is monitored by the P600 Precision Thermometer
(P/N 163961). The readout of the built-in sensor is compared with the read-out of the
thermometer.
FIGURE 4-6
Typical Result of the Oven Test
