Overview
ISO/TS 17307:2016 specifies a gas chromatography (GC) procedure for determining the total ester content of biodiesel (FAME - fatty acid methyl esters) using an external standard. The method is applicable to biodiesel esters in the carbon range C6–C26 and is intended to verify that total esters exceed 96.5 % (m/m). The procedure uses GC with a flame ionization detector (GC‑FID) and provides instructions for calibration, sample preparation, analysis and result expression.
Key topics and technical requirements
- Analyte scope: Total methyl esters (FAME); method can also quantify ethyl esters (FAEE) though precision for FAEE is not established.
- Range covered: Esters from C6 to C26. The method does NOT determine linolenic or other specific poly‑unsaturated alkyl ester contents (see Related standards).
- Instrumentation: GC with FID, on‑column injector (or equivalent), temperature‑programmed oven; typical detector temperature up to 380 °C.
- Column: Fused silica capillary, 30 m × 0.32 mm × 0.1 μm, stationary phase ~95% dimethylpolysiloxane / 5% phenyl‑methylpolysiloxane (high‑temperature capable).
- Calibration: External calibration using methyl (or ethyl) octadecanoate for most samples; when short‑chain esters (< C14) are present, a second calibration with methyl (or ethyl) dodecanoate is required. A minimum of six calibration points is recommended; acceptable regression coefficient > 0.999.
- Sample prep & injection: Typical sample mass ~0.1 g diluted in 26.8 g n‑heptane; injection volume 0.5 µL; integrate peaks from C6 to C26.
- Result expression: Total ester % (m/m) calculated from summed peak areas and calibration slope/intercept; reported to nearest 0.1 % (m/m).
- Precision & quality: Precision statistics and repeatability/reproducibility guidance are provided (interlaboratory assessment per ISO 4259). Normative sampling references: ISO 3170, ISO 3171.
Applications and users
- Quality control laboratories processing biodiesel batch release and conformity testing.
- Biodiesel producers verifying product ester content and feedstock independence.
- Regulatory and certification bodies assessing compliance with biodiesel specifications.
- R&D and analytical laboratories comparing feedstocks or optimizing production processes.
Practical benefits include a standardized GC‑FID workflow for confirming high ester purity, detecting incomplete transesterification or residual glycerides, and supporting product specification and trade.
Related standards
- EN 14103 - alternative technique for quantifying ester content (and specific unsaturates).
- EN 15779 - methods for poly‑unsaturated alkyl ester content.
- ISO 3170 / ISO 3171 - sampling of petroleum liquids.
- ISO 4259 - precision data and interlaboratory evaluation.
Note: Users must follow appropriate laboratory safety and regulatory practices when handling chemicals and high‑temperature GC equipment.