Measurement Protocol
Quantifying the concentration of potential chemical migrants requires determining the precise region of the packaging material that comes into contact with the food. Through surface area sampling, laboratories calculate the exact square decimetres of board exposed to the extraction solvent. This measurement is necessary because migration limits are legally defined in terms of milligrams of substance per square decimetre of packaging.
Calculation Rule
Applying this technique involves cutting a precise geometric shape from the test material using a calibrated die or cutter. For irregular or non flat packaging, the area must be calculated using mathematical models or by weighing a known paper template that matches the surface. Accurate area measurements prevent errors in the final concentration calculation, which could lead to an incorrect compliance decision.
Testing bodies use these calculated areas to convert the raw chromatographic peaks into regulatory units.
Quality Control
In high volume packaging lines, this measurement ensures that the ratio of printed area to food volume remains within safe design limits. Manufacturers perform surface area sampling during quality checks to monitor the application rate of coatings or adhesives. This process helps them maintain uniform barrier performance across the entire production run.
By keeping the treated surface area consistent, the company minimizes the risk of localized migration failures that could compromise food safety. The resulting data is also recorded in the product technical file to demonstrate due diligence to regulatory inspectors.
