Endress+Hauser Analytik Jena multi N/C, Руководство по эксплуатации, Страница: 31 / 106

multi N/C pharma UV Function and setup
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The correlation coefficient compares the dispersion of the calibration measuring points
of the regression function with the total dispersion of the calibration. If all calibration
measuring points are on the calculated regression function, then the correlation
coefficient is +1 or -1. For positive correlation coefficients the regression function is
increasing, for negative ones it is decreasing.
The square of the correlation coefficient is called the coefficient of determination.
As proof of the linearity of the calculated regression function an adaptation test
according to MANDEL is carried out in the control and analysis software multiWin.
Here the reduction of the residual variance is checked using a quadratic regression.
Variance homogeneity exists if the standard deviation is independent of the
concentration, i.e. the variance is constant over the whole calibration range. In the
control and analysis software multiWin the standard deviations of the calibration
range (smallest and largest concentration or volume) are examined.
If linearity and variance homogeneity are present, a linear regression can be assumed.
In this case it is possible to determine the verification, detection and determination
limits of the calibration. In the control and analysis software multiWin the calculation
rules of DIN 32645 (calibration rules) are used.
The verification limit of the calibration specifies the lowest concentration that can be
differentiated qualitatively from the zero point with a given probability. The
verification limit should always be smaller than the lowest calibration measuring point.
The detection limit of the calibration specifies the lowest concentration for which a
verification is possible with a given probability.
The determination limit of the calibration specifies the lowest concentration that can
be differentiated quantitatively from the zero point with a given probability.
3.4.5 Other calculations
For all measurements where multiple injections are carried out the average value (AV),
standard deviation (SD) and variation coefficient (VC) are calculated and displayed. For
each sample a tenfold determination can be carried out as a maximum.
The control and analysis software multiWin offers the option for an automatic outlier
selection. In the method a maximum limit for a variation coefficient or also for a
standard deviation can be entered.
The minimum number of measurements agreed in the method will be carried out. If
the distribution of the measured values is then above the agreed value (SD or VC)
additional injections are carried out from the same sample until the specified
maximum number of measurements has been reached.
After each measurement the variation coefficient or standard deviation are calculated
for all combinations of measurements. If the variation coefficient or the standard
deviation of at least one combination is smaller than the specified maximum variation
coefficient or standard deviation, no further measurements are carried out.
Correlation coefficient
Coefficient of
determination
Linearity
Variance homogeneity
Limit of detection
Detection limit
Limit of quantitation
Outlier selection