EN 14538 Fat and oil derivatives - Fatty acid methyl ester (FAME) - Determination of Ca, K, Mg and Na content by optical emission spectral analysis with inductively coupled plasma (ICP OES)
9 Sample analysis
9.1 Sample preparation
The sample is first homogenized thoroughly by vigorous shaking. Approximately 10 g sample is weighed, with a precision of 0.001 g, into a 100 ml PE bottle (5.1) and diluted with kerosene (4.2) up to a weight of approximately 20 g, with a precision of 0,001 g. Calculate the exact concentration, taking into account the exact weights. The resulting mixture is thoroughly homogenized by shaking. The exact dilution factor, DF (see 7.1), which is nominally 2,000 (20,000 g/10,000 g), is calculated and saved for the calculations in clause 10.
NOTE The reason for using the amount of kerosene listed in this clause instead of using paraffin oil as described for calibration is the attempt for minimization of differences in viscosity.
9.2 Measurement
The analysis of Ca and Mg and of Na and K is performed according to the instructions of the ICP manufacturer, using the wavelengths indicated in clause 5.3. For the measurement of Na and K, it is strongly recommended to take at least three readings from independent aspirations of the sample, of which the arithmetic mean is used as a single determination.
10 Calculation
The content of each element under investigation is calculated from the resulting signals by use of the inverse of the calibration function, taking into consideration the dilution factor, DF, which has been actually used in the measurement. This can be done either manually, or with use of the appropriate software functions of the ICP OES spectrometer. The sum of the contents of Calcium and Magnesium and the sum of the contents of Sodium and Potassium shall be calculated from the un-rounded contents of the corresponding single elements. When the content of one element is below the scope of the method (< 1 mg/kg), the content of the element is not considered in the calculation of the sum.
