Overview
ISO/TS 22115:2021 - "Animal and vegetable fats and oils - Separation of lipid classes by capillary gas chromatography (fingerprint method)" specifies a semi‑quantitative GC fingerprint method for screening oils, fats and oil/fat‑related samples (including deodistillates). The method provides main (e.g. triglycerides) and minor (e.g. sterols, sterol esters, tocopherols, wax esters, fatty alcohols, glycerol) component information in a single analysis. It is intended for screening and relative comparison of sample composition; truly quantitative determinations of pre‑identified classes should use class‑specific methods.
Key topics and technical requirements
- Principle: Hydroxylated compounds are converted to silyl derivatives and analysed by capillary gas chromatography with flame ionization detection (GC‑FID).
- Internal standard: 1,2,3‑tridecanoylglycerol prepared at 20 mg/ml in isooctane is used for semi‑quantitative calculations and response‑factor determination.
- Silylation: Reagent mixture of MSHFBA + methylimidazole (noting moisture sensitivity - prepare fresh and avoid storage beyond about one week).
- Reference standards: Individual 5 mg/ml solutions for representative compounds (e.g. oleic acid, mono‑/di‑/triglycerides, cholesterol, tocopherols, squalene, eicosanol, cholesterol palmitate) are used to determine response factors.
- GC hardware & conditions: High‑temperature fused‑silica capillary column (recommendation: 30 m, 0.25 mm i.d., 0.10 µm film, 100% dimethylpolysiloxane or similar), on‑column injector, FID, and a temperature program up to ca. 360 °C (detailed program in the specification). A 1 m empty pre‑column and solvent‑vent injection are suggested where available.
- Sample prep: Homogenization (melt if solid at 103 °C), dilution with internal standard in isooctane (or chloroform/toluene if needed), evaporation and silylation, reconstitution for 1 µl injection.
- Documentation: The TS includes procedures for response‑factor calculation, peak identification (Annex A chromatograms), interlaboratory test results (Annex B), and reporting requirements.
Applications and users
ISO/TS 22115:2021 is useful for:
- Quality control and routine screening in edible oil, cosmetic and oleochemical labs
- Authentication and comparative fingerprinting (composition profiling, adulteration screening)
- Research and method development in lipid chemistry and food science
- Deodistillate analysis and minor‑component screening
Typical users: analytical laboratories, food and oil manufacturers, research institutions and regulatory or conformity assessment bodies performing compositional screening of fats and oils.
Related standards
- ISO 661 - Preparation of test sample (referenced for sample preparation)
- Sampling guidance often refers to ISO 5555 (recommended for sampling procedures)
Keywords: ISO/TS 22115:2021, lipid classes, capillary gas chromatography, GC‑FID, fingerprint method, triglycerides, sterols, tocopherols, silylation, oil screening, semi‑quantitative analysis.