GE HEALTHCARE Biacore T100, Handbook

Page: 151 / 238

Biacore T100 Software Handbook BR-1006-48 Edition AE
151
Concentration analysis 8
• Examine the fitted curves in relation to the experimental data. Discard
samples where the fit is poor at one or both of the flow rates. As a general
guideline, the value reported for chi-squared should be less than about 5%
of the maximum response reached at the lowest flow rate (disregarding
the difference in units between chi-squared and response).
• Examine the statistical significance of the reported concentration as
indicated by the standard error or T-value (see Section 9.4.2). The standard
error should be 10% or less of the reported concentration (T-value greater
than 10). Discard samples where the standard error represents more than
20% of the reported concentration (T-value less than 5), and treat results
where the standard error is in the range 15–20% of the concentration (T-
value 5–10) with caution.
• Examine the values in the Measured Conc column. The operating range of
the method is approximately 0.05–5 µg/ml: values outside this range are
likely to be unreliable.
8.3.5 Fitting model
Evaluation of calibration-free concentration relies on fitting the data to a model
for 1:1 interaction (see Section 9.8.1) where the mass transport coefficient is
provided (through calculation from the diffusion coefficient, and flow cell
characteristics) and the analyte concentration is evaluated as a global variable.
Although this model is equivalent to the model for evaluation of 1:1 kinetics in
terms of the interaction description, the model for calibration-free
concentration analysis cannot be accessed through the model editor.
Notes: The diffusion coefficient for the analyte at the analysis temperature is
calculated automatically from the value at 20°C. The value at 20°C is
provided as an evaluation variable when the assay is run (Section B.2).
Parameters for calculating the mass transport coefficient from the
diffusion coefficient are fixed in the software.