Polyolefin Hydrocarbon Oligomer Migration Risk Screening
Polyolefin oligomer screening couples GC-FID envelope quantitation with diffusion modeling to clear POSH fractions against the 1.8 mg/kg food threshold.
POSH Screening
Meaning
Analytical protocol targeting the saturated oligomers naturally present in polyolefin resins. During posh screening, the lab identifies branched and cyclic hydrocarbons that might migrate into food from the plastic wall. Evaluation excludes molecules with more than fifty carbon atoms.
Hydrocarbon Source
Origin of these substances is the incomplete polymerisation of the monomer or the breakdown of the polymer during extrusion. Posh screening distinguishes these internal oligomers from external mineral oil contaminants like mosh or moah. Knowing the source allows the resin producer to optimize the reactor conditions to reduce these unwanted side products.
Toxicity Threshold
Determination of safety relies on comparing the total migration of these hydrocarbons to the limits set by health authorities. Posh screening provides the data needed to assess the risk of accumulation in human tissues. While most oligomers are considered inert, high concentrations can still affect the sensory properties of the packaged food.
Extraction Efficiency
Removal of the substances from the polymer matrix for testing requires the use of strong solvents and heat. Posh screening uses gas chromatography with flame ionisation detection to quantify the total amount of saturated hydrocarbons. This measurement is reported as a total mass per unit area of the packaging material.
The protocol is an essential part of the safety dossier for new polyolefin packaging materials.