Coulometric Titration Baseline Drift Calibration Methods
Drift calibration isolates cell background current from true sample moisture, preventing hydrolytic degradation and avoiding false incoming resin lot rejections.
Endpoint Criteria
Meaning
Control parameters determine the completion of a chemical reaction or moulding stage during quality control assays. These endpoint criteria establish when the moisture extraction from a polymer sample is complete, stopping the analysis. For hygroscopic resins like thermoplastic polyurethane, setting the correct stop condition prevents underestimation of water content.
Holding these precise limits ensures that only fully dry material enters the injection moulding screw.
Titration Termination
Chemical titrations run until the sensor detects a persistent excess of the reagent. The endpoint criteria for Karl Fischer analysis usually depend on a target voltage or a minimum drift rate. If these values are too lax, the measurement terminates prematurely, leaving residual water undetected in the polymer sample.
Such incomplete tests can result in cosmetic splay and lost strength in the final moulded part.
Moisture Assessment
Vapour extraction parameters must align with the desorption rate of the specific polymer matrix. Adjusting the endpoint criteria allows the lab to distinguish surface moisture from deeply bound water. For thick-walled regrind chips, the extraction takes longer than for thin virgin pellets.
Accurate stopping points ensure repeatable results across different resin batches.
Analytical Accuracy
Automated titrators rely on stable baseline conditions to apply stop limits. Lax endpoint criteria shorten the run time but compromise data integrity.