Meaning
Quantitative analytical procedures normalize analyte peak areas against a known concentration of a non-interfering reference substance added to samples prior to preparation. Analytical testing of polymer extracts relies on internal standard calibration to compensate for volumetric loss and injection variation during GC-MS and LC-MS analyses. This calibration framework governs quantitative precision across sample extraction and solvent concentration steps.
The technique requires an internal standard compound that mirrors the chemical behavior of target migrants while remaining absent from unspiked resin samples.
Response Factor
Relative response factors account for detector sensitivity differences between target analytes and reference compounds. Calculating response factors within internal standard calibration protocols ensures accurate concentration measurements across varying calibration ranges. Deuterated additives serve as ideal internal standards due to identical chemical properties and distinct mass-to-charge ratios.
Extraction Recovery
Solvent extraction of additives from dense polyolefin pellets often yields variable recovery efficiencies. Dosing internal standard calibration compounds directly into extraction solvent prior to refluxing corrects for incomplete additive recovery. Because target migrants and internal standards experience identical extraction losses, calculated analyte concentrations remain accurate.
Instrument Drift
Ion source contamination during long chromatographic sequences causes progressive signal decay. Applying internal standard calibration corrects for detector drift because signal decreases affect both target analyte and internal standard peaks proportionally. Uncorrected drift introduces severe quantification errors in automated round-the-clock testing runs.
