Overview
ISO/TS 17306:2016 specifies a gas chromatography (GC) procedure for the quantitative determination of free glycerin, total glycerin, and mono‑, di‑ and triacylglycerols in biodiesel. The method is applicable to biodiesel produced from most raw materials (including coconut, palm oil and animal fats), but excludes castor oil. It is primarily demonstrated for fatty acid methyl esters (FAME); applicability to other ester types is possible but precision has not been established.
Keywords: ISO/TS 17306:2016, biodiesel testing, glycerol determination, gas chromatography, FAME, free glycerin, total glycerin.
Key topics and technical requirements
- Analytical principle: Samples are derivatized by silylation (using MSTFA) and analyzed by GC with a flame ionization detector (GC‑FID). Identification uses retention time comparison with reference standards.
- Internal standards: Ethylene glycol for glycerol quantification and tricaprin for acylglycerols.
- Column and GC conditions: Typical fused‑silica capillary column (30 m × 0.32 mm × 0.1 µm, 95% dimethylpolysiloxane/5% phenyl), on‑column injector, temperature programming and detector/injector temperatures specified to achieve separation.
- Sample prep and calibration: Preparation of stock solutions, five calibration standards, MSTFA derivatization, dilution in n‑heptane, and replicate injections (minimum two).
- Performance and reporting: Calculation of free, bonded and total glycerol; precision data from an interlaboratory study included. Annexes provide check chromatograms and calculation guidance.
- Safety and sampling: Use appropriate safety protocols and obtain representative samples per ISO 3170/ISO 3171.
Practical applications and users
- Biodiesel producers and refineries - routine quality control and process optimization.
- Accredited testing laboratories - compliance testing against internal specs or regulatory requirements.
- Fuel regulators and standards bodies - verification of product quality for market surveillance.
- Engine and injector manufacturers - assessing potential deposit-forming components affecting fuel injection and engine durability.
- Research institutions - method validation, interlaboratory comparisons, and development for non‑FAME esters.
Benefits include reliable measurement of glycerol-related contaminants that can cause storage instability, injector fouling and engine deposits.
Related standards
- ASTM D6584 - alternative method for glycerol and acylglycerol determination in biodiesel.
- EN 14105 - European method for glycerol determination in FAME.
ISO/TS 17306:2016 offers a GC‑FID based, widely applicable approach for glycerol and acylglycerol quantification in biodiesel, useful for labs requiring robust analysis for product quality and engine protection.