Reference Chemical
Known concentrations of pure chemical compounds added to analytical samples compensate for sample loss and detector drift during chemical testing. Analytical laboratories introduce an internal standard into packaging extracts before gas chromatography or mass spectrometry analysis. Measurement procedures align with ISO 17025 validation protocols and EN 13628 standards for food contact material testing.
The method fails when the added standard compound reacts chemically with sample matrix components or co-elutes with target analytes.
Quantification Process
Laboratory technicians pipet precise amounts of standard compounds directly into raw packaging samples or solvent extracts prior to sample preparation. The standard undergoes identical extraction and injection steps as target analytes such as photoinitiators or residual monomers. Chromatographic software measures peak area ratios between target analytes and the standard chemical signal across calibration sequences.
Normalizing sample peak areas against internal standard responses corrects for volumetric variations caused by solvent evaporation or sample split injection fluctuations. Isotopically labeled analogs or structural isomers serve as standards due to matching chemical properties and distinct retention characteristics. Calibration curves built on response ratios maintain quantification accuracy despite minor sample handling losses.
Selection Limit
Selecting standard compounds with retention times overlapping target packaging migrants prevents accurate peak integration. Standard purity below ninety-nine percent introduces signal baseline contamination and distorts quantification calculations.
