BS EN 14110 Fat and oil derivatives - Fatty Acid Methyl Esters (FAME) - Determination of methanol content
5 Procedure
5.1 Analytical conditions
The GC working conditions shall be chosen taking into account the characteristics of the column and the type of carrier gas to reach the desired resolution which is fixed at minimum 1.5 for the methanol and 2-propanol peaks.
NOTE 1 The following parameters are given as an example:
column DB1 (length = 30 m, internal diameter = 0.32 mm, film thickness = 3 µm);
split injector (flow rate: 50 ml/min);
injector and detector temperature: 150°C;
oven and column temperature: 50 °C;
carrier gas (hydrogen) pressure: 40 kPa;
volume injected: 500 µl.
NOTE 2 The following head space sampling conditions are given as an example:
equilibrium temperature: 80 °C;
equilibrium time: 45 min;
sampling volume: 500 µl.
5.2 Operation
The gas chromatograph shall be set up and operated according to the manufacturer's instructions.
6 Calibration solutions
Three calibration solutions with approximately the following methanol concentrations in FAME (3.3) shall be prepared as described below.
NOTE Three calibration solutions have proven sufficient in daily practise for a reliable coverage of the concentration range given in the scope of this method. For other concentration ranges, it is also possible to use other or more calibration solutions.
6.1 Calibration solution A (0.5 % (m/m) methanol in FAME).
Fill a 25 ml volumetric flask with 25 ml of FAME (3.3) and add (112 +/- 0.1) mg (142 µl) methanol into the liquid phase using a syringe (4.3), the addition being made into the liquid phase. The exact masses shall be determined by weight measurement. It is necessary to ensure thorough mixing by vigorous shaking.
6.2 Calibration solution B (0.1 % (m/m) methanol in FAME).
Transfer 5 ml of calibration solution A into a 25 ml analytical flask and carefully fill to the mark with FAME (3.3).
6.3 Calibration solution C (0.01 % (m/m) methanol in FAME).
Transfer 1 ml of calibration solution B into a 10 ml analytical flask and fill to the mark with FAME (3.3).
