Surrogate Chemical Selection Rules for Post Consumer Polyolefin Decontamination Testing
Surrogate selection for polyolefin challenge testing requires five distinct volatility and polarity classes to validate core matrix decontamination.
POSH Interference
Meaning
Analytical disruptions occurring when polyolefin oligomeric saturated hydrocarbons overlap with mineral oil saturated hydrocarbons during chromatographic testing. Lab results often suffer from posh interference because the chemical structures of the polymer fragments are nearly identical to those of petroleum based lubricants. This overlap makes it difficult to determine if a food package is contaminated by external oils or simply contains its own low molecular weight resins.
Analytical Difficulty
Separating the two groups of hydrocarbons requires specialized columns and precise temperature programming. Because posh interference creates a broad hump on the chromatogram, the area under the curve cannot be easily assigned to a single source. Chemists use multidimensional chromatography to improve the resolution between the migrating oligomers and the external contaminants.
Advanced software techniques are then applied to subtract the known polymer signal from the total hydrocarbon count.
Material Distinction
Virgin polyolefins typically contain a predictable distribution of these oligomers based on the catalyst used during polymerization. When posh interference occurs in recycled resins, the presence of varied resin grades complicates the baseline. Understanding the native oligomer profile of the resin is necessary for accurate safety reporting.
Barrier Performance
Effective coatings or functional layers can prevent both mineral oils and polymer oligomers from reaching the food. If posh interference is detected, the packager may need to upgrade to a high barrier film to meet migration limits. The cost of these materials is weighed against the risk of regulatory rejection.