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ISO 12873-2010 pdf free download
ISO 12873-2010 pdf free download.Olive oils and olive-pomace oils Determination of wax content by capillary gas chromatography
Huiles d’olive et huiles de grignons d’olive — Determination de Ia teneur en cires par chromatographie en phase gazeuse sur colonne capillaire.
9.1 Preparation of the chromatography column
Suspend 15 g of silica gel (51) in n-hexane (5.2) and introduce into the chromatography column (6.2). Allow to settle spontaneously, Use an electric shaker (6.5) to assist in complete settling to make the chromatographic band more homogeneous. Percolate 30 ml n-hexane to remove any impurities. Weigh, to the nearest 0,1 mg, about 500mg of the sample into a 25 ml Erlenmeyer flask (6.1). add a suitable amount of internal standard (5.5) depending on the assumed wax content. Add 0.1 mg of lauryl arachidate in the internal standard solution (5.5) in the case of olive oil, and 0,25 mg to 0,50 mg in the case of olive-pomace oil.
Transfer the test portion to the chromatographic column with the aid of two 2 ml portions of n-hexane.
Allow the solvent to drain off to 1 mm above the upper level of the absorbent. Percolate a further 70 ml of n-hexane to remove any n-alkanes naturally present. Then start chromatographic elution by collecting 180 ml of a mixture of 99 mi/lOC ml n-hexane (5.2) and 1 ml/100 ml diethyl ether (5.3) at a rate of about 15 drops every 10 s. Perform the column chromatography at room temperature.
Prepare the n-hexane-diethyl ether mixture freshly every day.
To check visually that the waxes have been completely eluted, add 100 jil of Sudan I dye (5.6) solution at a concentration of 1 g/100 ml to the test portion solution. The dye is retained on the chromatographic column between the waxes and triglycerides. Hence, when the dye reaches the bottom of the column, suspend elution because all the waxes have been eluted.
Evaporate the resultant fraction in a rotary evaporator (6.6) until the solvent is almost removed. Remove the last 2 ml of solvent under a weak stream of nitrogen, then add 2 ml to 4 ml of n-heptane.
9.2 Gas chromatographic analysis
9.2.1 Preliminary procedure
If the column is being used for the first time, it is advisable to condition it. Run a light flow of gas through the column, then switch on the gas chromatograph. Heat gradually for approximately 4 h until a temperature of 350 °C is reached
Maintain this temperature for at least 2 h, then regulate the apparatus to the operating conditions (gas flow, light flame, oven temperature for column, detector, etc.). Record the signal at a sensitivity that is at least twice as high as that required for the analysis. The baseline should be linear, with no peaks of any kind, and shall not drift. Negative straight-line drift indicates incorrect column connections, while positive drift is symptomatic of improper column conditioning.ISO 12873-2010 pdf free download.
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