Meaning
Coupled analytical systems link a liquid separation stage directly to a gas chromatograph to automate sample transfer without manual intervention. This configuration of on-line liquid chromatography allows for the direct fractionation and analysis of complex mixtures, such as mineral oils in polymers. It minimizes the loss of volatile analytes and prevents external contamination during the preparation steps.
The process is used in advanced testing laboratories, finding its limit in the high capital cost of the coupled instrumentation.
Method Integration
Modern laboratories integrate liquid chromatography with gas chromatography to achieve high-resolution separation of oils and polymer additives. In this coupled setup, on-line liquid chromatography separates the mineral oil saturated hydrocarbons from the mineral oil aromatic hydrocarbons before their introduction into the gas chromatograph. This direct transfer removes the need for solvent evaporation and manual sample handling.
It speeds up the throughput of migration tests for food-contact plastics.
Process Monitoring
Sourcing plastic resins requires verifying that the raw materials do not contain hazardous chemical migrants. Utilizing on-line liquid chromatography provides rapid feedback on the purity of incoming polymer batches. This real-time detection ensures that only compliant materials reach the moulding floor.
Resin Economics
Recycled polymer use in packaging is constrained by the presence of migrating contaminants from past use cycles. Evaluating these recycled batches with on-line liquid chromatography allows recyclers to sort materials based on contamination levels, optimizing their blending processes. It helps maintain the balance of virgin and regrind resins, reducing material costs without compromising safety.
This screening protects converters from using contaminated batches that would violate safety standards and cause expensive product recalls or regulatory penalties.
