BS EN 14105 Fat and oil derivatives - Fatty Acid Methyl Esters (FAME) - Determination of free and total glycerol and mono-, di-, triglyceride contents
5 Preparation of solutions
5.1 1,2,4-Butanetriol stock solution, 1 mg/ml
Accurately weigh approximately 50 mg (accuracy +/- 0.1 mg) of 1,2,4-butanetriol (3.6) in a 50 ml volumetric flask (4.3) and make up to the mark with pyridine (3.2).
5.2 Glycerol stock solution, 0.5 mg/ml
Accurately weigh approximately 50 mg (accuracy +/- 0.1 mg) of glycerol (3.5) in a 10 ml volumetric flask (4.5) and make up to the mark with pyridine (3.2). Using a pipette (4.7), transfer 1 ml of this solution into a 10 ml volumetric flask (4.5) and make up to the mark with pyridine (3.2).
5.3 Standard glycerides stock solution, 2.5 mg/ml
For each reference glyceride, monononadecanoate (3.7), dinonadecanoate (3.8) and trinonadecanoate (3.9), accurately weigh approximately 50 mg (accuracy +/- 0.1 mg) in a unique 20 ml volumetric flask (4.4) and make up to the mark with tetrahydrofurane (3.3).
The solution shall be perfectly limpid at ambient temperature. After storage in refrigerator at 4 °C the solution might show a precipitate that must re-dissolve spontaneously when restored at ambient temperature, without any external heating.
NOTE If stored at 4 °C the solution is stable for almost 3 months.
5.4 Commercial mixture of monoglycerides
Made up of mono-palmitoylglycerol (monopalmitin), mono-stearoylglycerol (monostearin) and of mono-oleoylglycerol (monoolein), present in quantities having an identical mass.
Prepare a stock solution of this mixture by weighing approximately 100 mg in a 10 ml volumetric flask (4.5) and make up to the mark with pyridine (3.2).
This solution may be used to locate the relevant peaks in GC paths.
5.5 Calibration solutions
Prepare four calibration solutions by transferring into a series of vials (4.6) the volumes of stock solutions of glycerol (5.2) and of 1,2,4-butanetriol (5.1) given in Table 1, using the 100 µl microsyringes (4.8). Do not use syringe at maximum capacity, but dispense the half volume twice (i.e.: in case of 100 µl dosing using a 100 µl syringe, load 50 µl twice). Make sure that needle and body of the syringe are free from air bubbles, and measure volumes only by difference (i.e.: when dispensing 80 µl, fill syringe up to 100 µl and supply solution up to the 20 µl mark).
6 Sampling
Samples shall be taken in accordance with the requirements of national standards or regulations for the sampling of the product under test. A recommended sampling method is given in EN ISO 5555 or EN ISO 3170.
