ISO 10565 pdf download.Oilseeds — Simultaneous determination of oil and water contents — Method using pulsed nuclear magnetic resonance spectrometry
1 Scope
This International Standard specifies a rapid method for the determination of the oil and water contents of commercial oilseeds using pulsed nuclear magnetic resonance (NMR). It is applicable to rapeseeds, soya beans, linseeds and sunflower seeds with a water content less than 1 0 %. For seeds with higher water contents, drying is necessary before the oil content can be determined by pulsed NMR. NOTE 1 This method has been tested with rapeseeds, soya beans, linseeds and sunflower seeds. This does not, however, preclude its applicability to other commercial seeds whose oil is liquid at the temperature of measurement. NOTE 2 The reproducibility values are generally higher than those obtained by the drying method (ISO 665).
2 Normative references
The following standards contain provisions which through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 659:1 988, Oilseeds — Determination of hexane extract (or light petroleum extract), called “oil content”. ISO 664:1 990, Oilseeds — Reduction of laboratory sample to test sample. ISO 665:1 977, Oilseeds — Determination of moisture and volatile matter content.
3 Principle
Insertion of the test sample into the magnetic field of a pulsed NMR spectrometer. Application of an alternating electromagnetic field in the form of an intense 90° radiofrequency (RF) pulse which excites all the hydrogen nuclei. Recording of the free induction decay (FID) following the 90° pulse. The maximum amplitude of this signal is proportional to the total number of protons from the water and oil phases of the sample.Application of the second RF pulse, a so-called 1 80° pulse, to produce a spin-echo signal when only the signal from the oil phase contributes to the FID. NOTE 1 The maximum amplitude of this echo signal is proportional to the oil content. It varies with the sample temperature following a complex law. An increase in temperature decreases the measured value of the echo. Calculation of the difference between the two amplitudes, which is proportional to the water content. Automatic conversion of the measured signals, after suitable calibration of the apparatus, into percentages of oil or water. NOTE 2 Simultaneous indications of the oil and water contents can be given by some spectrometers equipped with a minicomputer and a specific program.
4 Calibration samples
Calibration samples shall be homogeneous and free from impurities. A definition of impurities is given in ISO 658 [1 ]. 4.1 Samples for moisture-content calibration In order to obtain a reliable calibration curve, it is recommended that the water contents of the calibration samples be less than 1 0 % for all seeds. The water content of seeds can vary depending on storage conditions. Water content shall therefore be determined in accordance with ISO 665 just prior to calibration. 4.2 Samples for oil-content calibration Samples of oilseeds shall be of the same species as the test samples and of similar fatty acid compositions (for instance for the analysis of rapeseeds which are rich in erucic acid, or sunflower seeds which are rich in oleic acid). Oil content shall be determined using the reference method specified in ISO 659.
5 Apparatus
Usual laboratory apparatus and, in particular, the following. 5.1 Pulsed low-resolution NMR spectrometer, suitable for measurement of the oil content and water content of oilseeds, and meeting the precision requirements of 1 1 .2 and 1 1 .3. The instrument’s parameters shall be in accordance with the instructions/specifications from the manufacturer. CAUTION — Remove metallic objects from the proximity of the NMR spectrometer. 5.2 Sample tubes, made of glass, suitable for use with the NMR spectrometer. 5.3 Analytical balance, electronic, capable of weighing to an accuracy of ±0,01 g. This equipment may be linked to the NMR spectrometer so that the sample mass is recorded directly by the NMR, or linked to a minicomputer (see NOTE 2 in clause 3). 5.4 Drying oven, capable of being maintained at 1 03 °C ± 2 °C. 5.5 Dishes, made of glass or metal, of diameter 7 cm to 1 0 cm, and provided with lids.