Meaning
Mathematical technique used in thermal analysis and titration to define the starting point for integrating a signal curve. Baseline extrapolation allows for the separation of the actual moisture or energy peak from the background noise and drift of the instrument. Precise determination of the starting value ensures that the resulting area calculation reflects only the sample properties.
Mathematical Application
Linear regression applied to the stable portion of the signal before the sample injection provides a predicted path for the background value. During a Karl Fischer titration using an oven, the carrier gas contributes a small but constant amount of drift. The software subtracts this value from the total iodine consumed to isolate the water from the resin.
Thermal Analysis
Integration of heat flow peaks in differential scanning calorimetry relies on this method to determine the enthalpy of melting. Without a clearly defined start and end point, the area under the curve cannot be calculated precisely. Moulders use these values to verify the crystallinity of parts and the effectiveness of nucleating agents.
Measurement Accuracy
Errors in the slope of the projected line lead to substantial variations in reported moisture content or glass transition temperatures. When the background is unstable, the software might truncate the measurement too early or run it too long. Consistent sample preparation and stable environmental conditions are required to ensure that the projected baseline remains valid throughout the test run.
