Meaning
A quantitative range expressing the doubt associated with a measured chemical concentration in polymer extractable and leachable testing. Quantification of analytical uncertainty establishes the boundary within which the true value of a migrant, such as a plasticiser or oligomer, resides at a stated confidence interval. Laboratory protocols derive this value from calibration drift and recovery rates.
Beyond this defined range, a measurement cannot legally or technically confirm whether a resin or packaging film complies with regulatory migration limits.
Error Margin
Laboratory measurements on moulded parts or barrier films incorporate systematic and random variability from sample preparation and solvent extraction. Incorporating analytical uncertainty into food contact compliance decisions prevents false passes where a migrant concentration sits near a statutory threshold. A measured value of nine milligrams per kilogram with a ten percent error range spans from eight point one to nine point nine milligrams.
Calibration curves constructed across multiple days capture detector drift and solvent purity variations. Compliance certification requires the upper bound to remain below the legal limit.
Value Variance
Replicate injections of virgin resin extracts demonstrate inherent instrument dispersion caused by ion source fouling or column degradation over extended sequences. When testing recycled polyolefin flakes, background contamination shifts baseline integration boundaries, raising the calculated dispersion. Moulders must account for this shift when comparing certificate of analysis values against internal quality thresholds.
Limit Compliance
Dispute resolution between material vendors and converters relies on agreed statistical confidence intervals applied to chromatographic yield figures. Without harmonized protocols for analytical uncertainty, two accredited test facilities can report divergent pass or fail statuses for the same lot of packaging film. Contractual agreements therefore specify both the analytical technique and the accepted confidence interval for non-intentionally added substances.
