ISO-10565-1998.pdf

A Reference number ISO 10565:1998(E) INTERNATIONAL STANDARD ISO 10565 Second edition 1998-08-15 Oilseeds Simultaneous determination of oil and water contents Method using pulsed nuclear magnetic resonance spectrometry Graines oléagineuses Détermination simultanée de la teneur en huile et en eau Méthode par spectrométrie par résonance magnétique nucléaire pulsée Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:31:28 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10565:1998(E) © ISO 1998 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case postale 56 CH-1211 Genève 20 Switzerland Internetisoiso.ch Printed in Switzerland ii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non- governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 10565 was prepared by Technical Committee ISO/TC 34, Agricultural food products, Subcommittee SC 2, Oleaginous seeds and fruits. This second edition cancels and replaces the first edition (ISO 10565:1993), which has been technically revised. Annexes A and B of this International Standard are for information only. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:31:28 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD © ISOISO 10565:1998(E) 1 Oilseeds Simultaneous determination of oil and water contents Method using pulsed nuclear magnetic resonance spectrometry 1Scope 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 10 %. 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). 2Normative 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 659:1988, Oilseeds Determination of hexane extract (or light petroleum extract), called “oil content“. ISO 664:1990, Oilseeds Reduction of laboratory sample to test sample. ISO 665:1977, Oilseeds Determination of moisture and volatile matter content. 3Principle 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. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:31:28 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10565:1998(E) © ISO 2 Application of the second RF pulse, a so-called 180° 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. 4Calibration samples Calibration samples shall be homogeneous and free from impurities. A definition of impurities is given in ISO 658 1. 4.1Samples 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 10 % 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. 4.2Samples 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. 5Apparatus Usual laboratory apparatus and, in particular, the following. 5.1Pulsed low-resolution NMR spectrometer, suitable for measurement of the oil content and water content of oilseeds, and meeting the precision requirements of 11.2 and 11.3. 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. 5.2Sample tubes, made of glass, suitable for use with the NMR spectrometer. 5.3Analytical 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). 5.4Drying oven, capable of being maintained at 103 °C ± 2 °C. 5.5Dishes, made of glass or metal, of diameter 7 cm to 10 cm, and provided with lids. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:31:28 MDTNo reproduction or networking permitted without license from IHS -,-,- © ISO ISO 10565:1998(E) 3 5.6Desiccator, containing an efficient desiccant. 6Sampling Sampling is not part of the method specified in this International Standard. A recommended sampling method is given in ISO 542 2. It is important that the laboratory receive a sample which is truly representative and has not been damaged or changed during transport or storage. 7Preparation of test sample Prepare the test sample in accordance with ISO 664. Remove from the prepared test sample all metallic objects (e.g. staples, needles, etc.). Whole seeds shall be homogeneous and, as far as possible, free from impurities. 8Calibration procedure 8.1General 8.1.1 Use the set-up parameters of the NMR spectrometer (5.1) recommended by the manufacturer and optimize them by preliminary tests. For all calibration and measurement operations, follow the user's manual. Ensure that all operations during calibration and measurement are carried out under the same conditions and, in particular, at the same temperature (±2 °C). A minimum of three calibration samples is necessary, although more than three samples may be used. 8.1.2 Enter the parameters for the measurements (pulse sequence, attenuation, etc.) of the oil or water content (as applicable) into the NMR spectrometer, following the manufacturer's recommendations, and specify a code number under which the calibration curve is to be stored. The total measurement time shall be a minimum of 16 s. 8.1.3 Set the apparatus to the calibration mode. 8.1.4 Introduce a portion of the first calibration sample into a tared sample tube (5.2) up to the optimum height specified by the manufacturer. Transfer the value of the sample mass from the balance to the NMR spectrometer. NOTE A manual feed of the mass ot the calibration sample into the NMR spectrometer is also possible. 8.1.5 Enter, as applicable, the value of either the water content (as a percentage by mass) or the oil content (as a percentage by mass) into the spectrometer. 8.1.6 Introduce the sample tube containing the first calibration sample into the measuring head. Record automatically or manually the water or oil values thus obtained. 8.1.7 Repeat steps 8.1.4 to 8.1.6 for the two (or more) other calibration samples. 8.1.8 Calculate automatically or manually the calibration parameters of the calibration curve using the results obtained in 8.1.6 and 8.1.7. The correlation coefficient shall normally be greater than 0,95. If this is not the case, check the values obtained using the reference methods specified in ISO 659 and ISO 665 respectively, or repeat the calibration procedure using three (or more) other calibration samples. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:31:28 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10565:1998(E) © ISO 4 Store the calibration curve under the code number chosen in step 8.1.2. 8.1.9 Complete the oil-content calibration curve by using an empty tube and by repeating steps 8.1.4 to 8.1.6. This part of the method is not applicable to the water content calibration curve. 8.2 Calibration procedure for the determination of water content 8.2.1 Procedure A: Three calibration samples with known water contents To obtain a reliable calibration graph, it is necessary that the water contents of the calibration samples span the largest possible range. However, a water content of 0 is not permissible. Follow the general procedure specified in 8.1.1 to 8.1.8. 8.2.2 Procedure B: One calibration sample with known water content NOTE In this calibration procedure, the quantity of water detected by the NMR spectrometer is varied by varying the height to which the sample tubes are filled with the calibration sample. 8.2.2.1 Follow the general procedure specified in 8.1.1 to 8.1.3. 8.2.2.2 Introduce into three tared sample tubes (5.2) portions of the calibration sample with known water content to approximate heights of 35 mm, 30 mm and 25 mm (20 mm minimum) and weigh them. Note the corresponding masses, in grams, as m1, m2 and m3. NOTE Three calibration points is the minimum for establishing the calibration curve. 8.2.2.3 Calculate the relative water content, w, as a percentage by mass, of each of the three portions of the calibration sample as follows: w mW m 1 1 1 = × w mW m 2 2 1 = × w mW m 3 3 1 = × where m1, m2 and m3are the masses, in grams, of the three portions of the calibration sample in each of the three tubes, where m1 is the largest mass; Wis the water content, as a percentage by mass, of the calibration sample, determined in accordance with ISO 665. 8.2.2.4 Enter into the NMR spectrometer the value, m1, of the mass of the first portion. 8.2.2.5 Enter into the NMR spectrometer the value, w1, of the relative water content of the first portion. 8.2.2.6 Insert the tube containing the first portion of the calibration sample into the measuring head and carry out the determination. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/21/2007 02:31:28 MDTNo reproduction or networking permitted without license from IHS -,-,- © ISO ISO 10565:1998(E) 5 8.2.2.7 Repeat the operations described in 8.2.2.4 to 8.2.2.6 with the two other portions of the calibration sample, always entering m1 in step 8.2.2.4, then the respective relative water contents w2 and w3 in step 8.2.2.5. 8.2.2.8 Calculate the calibration parameters in accordance with step 8.1.8. 8.3 Calibration procedure for the determination of oil content 8.3.1 Procedure A: Three calibration samples with known oil contents Use the samples specifies in 4.1. Follow the general procedure specified in 8.1.1 to 8.1.9. 8.3.2 Procedure B: One calibration sample with known oil content NOTE In this calibration procedure, the quantity of oil detected by the NMR spectrometer is varied by varying the height to which the sample tubes are filled with the calibration sample. 8.3.2.1 Follow the general procedure specified in 8.1.1. 8.3.2.2 Introduce into three tared sample tubes (5.2) portions of the calibration sample with known oil content to approximate heights of 35 mm, 30 mm and 25 mm (20 mm minimum) and weigh. Note the corresponding masses, in grams, as m1, m2 and m3. 8.3.2.3 Calculate the relative oil content, h, as a percentage by mass, in the three portions of the calibration sample as follows: h mH m 1 1 1 = × h mH m 2 2 1 = × h mH m 3 3 1 = × where m1, m2 and m3are the masses, in grams, of the three portions of the calibration sample; His the oil content, as a percentage by mass, of the calibration sample, determined in accordance with ISO 659. 8.3.2.4 Follow the general procedure specified in 8.1.2 to 8.1.8, entering the value of the oil content, in grams, in step 8.1.5. 8.3.2.5 Enter into the NMR spectrometer the value, m1, of the mass of the first portion. 8.3.2.6 Enter into the NMR spec