Meaning
Chemical markers introduced into a recycling process to measure the cleaning efficiency of the decontamination step. Challenge test surrogates simulate the behavior of real-world contaminants like detergents, solvents or fuels that might be present in post-consumer waste. The test is successful if the concentration of these markers is reduced by the required factor during the washing and extrusion cycles.
Contamination Simulation
Selection of specific molecules ensures that the test covers different polarities and molecular weights. Challenge test surrogates often include substances like benzophenone or toluene to represent a wide range of potential pollutants. These chemicals are spiked into the flake at high concentrations before the decontamination process begins.
Safety Verification
Regulatory bodies use the removal rate of these chemicals to grant letters of non-objection for food-contact applications. Challenge test surrogates provide a quantifiable measure of the safety margin provided by a recycling technology. If the system fails to remove the surrogates to a safe level, the resulting regrind cannot be used for direct food contact.
Protocol Design
Execution of the test requires precise control over temperature and vacuum settings in the reactor. Challenge test surrogates are measured at the input and the output of the machine using gas chromatography. This data allows the operator to set the minimum processing parameters needed for consistent purification.
The surrogates must be safe for laboratory personnel to handle during the spiking phase.
