Chemical Biomarker
Saturated tetracyclic hydrocarbons represent stable chemical structures used to identify heavy mineral oil fractions in packaging. Within trace analysis of paper and board, cholestane is utilized as an internal standard to quantify mineral oil saturated hydrocarbons. This high-molecular-weight compound behaves similarly to the heavy wax fractions found in recycled paperboard fibers, allowing accurate trace measurement.
Analytical Quantification
Chromatographic determination of hydrocarbon migration requires robust reference standards that elute late in the chromatogram to avoid overlap with volatile solvents. Because cholestane features a high boiling point and a distinct molecular structure, it elutes after the bulk of lighter mineral oil saturated hydrocarbons, providing a clear reference peak. Technicians add a known concentration of this substance to the extracted sample to correct for injection volume variations and instrument drift.
This measurement process ensures that calculations of mineral oil content in the finished packaging remain precise and reproducible across different testing batches and laboratories.
Matrix Interference
Complex fiber mixtures from recycled paperboard often yield interference during extraction. Adding cholestane allows laboratories to confirm the efficiency of the cleanup step on silica gel columns, which separates saturated hydrocarbons from aromatic fractions. Poor column recovery is easily identified by a depleted standard signal, indicating the need to refine the purification step.
