ISO-10540-3-2002.pdf

Reference number ISO 10540-3:2002(E) © ISO 2002 INTERNATIONAL STANDARD ISO 10540-3 First edition 2002-12-01 Animal and vegetable fats and oils Determination of phosphorus content Part 3: Method using inductively coupled plasma (ICP) optical emission spectroscopy Corps gras d'origines animale et végétale Détermination de la teneur en phosphore Partie 3: Méthode par spectrométrie d'émission optique avec plasma induit par haute fréquence Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10540-3:2002(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat accepts no liability in this area. Adobe is a trademark of Adobe Systems Incorporated. Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. © ISO 2002 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 either ISO at the address below or ISO's member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii © ISO 2002 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10540-3:2002(E) © ISO 2002 All rights reserved iii 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. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. 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. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 10540-3 was prepared by Technical Committee ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable fats and oils. ISO 10540 consists of the following parts, under the general title Animal and vegetable fats and oils Determination of phosphorus content: Part 1: Colorimetric method Part 2: Method using graphite furnace atomic absorption spectrometry Part 3: Method using inductively coupled plasma (ICP) optical emission spectroscopy Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 10540-3:2002(E) © ISO 2002 All rights reserved 1 Animal and vegetable fats and oils Determination of phosphorus content Part 3: Method using inductively coupled plasma (ICP) optical emission spectroscopy 1 Scope This part of ISO 10540 specifies a method for the quantification of phosphorus in oil, which is limited to oils with low phosphorus content, without any turbidity or visible sediment. Depending on the dilution solvent used, most types of vegetable oils can be analysed (crude, degummed, refined, bleached, deodorized and hardened oils) and nearly all types of lecithins and phosphatides. This method is only suitable when phosphorus is present in a solubilized form. When it is present as fine particles, such as bleaching earth, ICP-OES analysis results in poor recovery as a result of nebulization and atomization problems. The only suitable non-ashing direct method for these samples is graphite furnace atomic absorption spectrometry. ISO 10540-1 is the reference (colorimetric) method for the determination of the phosphorus content in fats and oils. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 661, Animal and vegetable fats and oils Preparation of test sample 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 phosphorus content dissolved phosphorus measured according to the method specified in this part of ISO 10540 NOTE It is measured in milligrams per kilogram. 4 Principle Solvent-diluted vegetable oils are analysed for phosphorus by direct aspiration. Liquid samples are nebulized and carried into the excitation source by a flowing gas. Atoms are quantified by measuring the specific emission lines produced by atoms decaying from high energy levels. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10540-3:2002(E) 2 © ISO 2002 All rights reserved 5 Reagents Use only reagents of recognized analytical grade, unless otherwise specified. 5.1 Butanol. 5.2 Kerosene. 5.3 Xylene. 5.4 Standard element, present in solution as an organic soluble material1). 5.5 Base oil (Base 20 or Base 75 Oil)1), used to check the blank oil used and for the dilution of the standard solutions as needed. 6 Apparatus Usual laboratory equipment and, in particular, the following. 6.1 Inductively coupled plasma optical emission spectrometer. 6.2 Analytical balance, capable of weighing to the nearest 0,001 g and displaying 0,000 1 g. 6.3 Oven, capable of maintaining a temperature of 60 °C ± 2 °C. 6.4 Tilt table mixer. 6.4 Volumetric flasks, of 100 ml capacity. 7 Sampling It is important that the laboratory receive a sample that is truly representative and has not been damaged or changed during transport and storage. Sampling is not part of the method in this International Standard. A recommended sampling method is given in ISO 5555. 8 Preparation of test sample Prepare the test samples in accordance with ISO 661, except that the samples should not be clarified. If the sample is not clear when liquid, this method should not be used. 1) SPEX, 203 Norcross Ave., Metuchen, NJ 08840 (908/549-7144) and Base 20 Oil or Base 75 Oil and Constan brand standards available from Accu-Standard, 25 Science Park, New Haven, CT 06511 (800-442-5290) are examples of suitable products available commercially. This information is given for the convenience of users of this part of ISO 10540 and does not constitute an endorsement by ISO of these products. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10540-3:2002(E) © ISO 2002 All rights reserved 3 9 Procedure 9.1 General 9.1.1 Dilute all samples, standards and blanks 1:1 (by mass) with 1-butanol (or kerosene/xylene) to reduce the viscosity of the oil for better nebulization. Some samples are more soluble in 1-butanol than others. NOTE 1 1-Butanol is preferred because it has better moisture tolerance and allows a higher flow rate with higher pressure than kerosene without extinguishing the torch. The increased moisture tolerance permits the analysis of crude oils and lecithins without phase separation. The higher flow rate provides for improved detection limits. 9.1.2 Melt solid samples at approximately 10 °C above their melting point and mix prior to dilution. Keep the diluted sample warm and monitor throughout the analysis to ensure that it remains in solution. The maximum temperature for the analysis of hardened fats is 60 °C. 9.1.3 Precise operating conditions will vary from instrument to instrument. Operate your instrument according to the manufacturers directions and specifications. Conditions used for identical instruments from the same manufacturer will vary depending on the type of nebulizer and pumping system used. If kerosene or xylene is used, all instrumental operating conditions, such as pump flow rate, will change from those set for 1-butanol. Therefore, the analysis shall be standardized and all analyses run with all standards, blank and samples dissolved in the same solvent. NOTE 2 Some of the conditions used in the collaborative study are given in Annex B. 9.1.4 Ignite the instrument and allow it to warm up. It is profiled on an internal Hg lamp. Phosphorus may be detected at the major emission lines of 178,2 nm, 213,6 nm or 214,9 nm. Limits of detection are approximately 0,5 mg/kg. 9.1.5 Standardize the instrument as described (9.3) and scan all the samples in triplicate. NOTE 3 Calibration drift has been noted. It may result from carbon build-up on the injector tip. 9.2 Preparation of standards 9.2.1 Blank Typically, refined and bleached soya bean, or another oil that has been shown to be free of trace elements, is used. Blank oil is diluted 1:1 as described in 9.1.1. Base 20 or Base 75 oil (5.5) is used as an absolute reference blank to determine that the blank oil is free of trace elements. 9.2.2 Phosphorus standard solution The phosphorus standard is prepared from commercially available single-element organic-based standard. Weigh accurately the standard and add enough blank oil to total 50,00 g. Add 50,00 g of solvent (1-butanol, kerosene or xylene) to achieve a 1:1 dilution. Although one standard concentration will work, up to four standards will provide a better calibration for linearity and accuracy. Levels should include 2,5 mg/kg, 5,0 mg/kg and 10,0 mg/kg standards depending on the range of values expected. If an internal standard is used, it may be weighed as part of the elements or incorporated as part of the dilution solvent to yield 10 mg/kg to match that amount added to the sample. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 10540-3:2002(E) 4 © ISO 2002 All rights reserved 9.3 Standardization Run the blank oil standard and diluted Base 20 or Base 75 oils at the specified wavelength for phosphorus. Run the phosphorus standard solutions (9.2.3) at the phosphorus wavelength chosen. Scan blanks, samples and standards in triplicate for phosphorus and average them. Run standards and the blank every 10 samples or less and restandardize the instrument as needed. For accuracy use a narrow range of standardisation (0 mg/kg to 25 mg/kg of phosphorus). Although the linearity is somewhat greater, test samples should be diluted to keep the phosphorus content within the range of standardization. 9.4 Preparation of test samples Weigh 2,5 g (± 0,02 g) of sample into an autosampler tube and dilute with 2,5 g of 1-butanol (kerosene or xylene) delivered from an automatic pipette. Cap the tube and invert 40 to 50 times on a mixing table. Dilute 0,2 g of lecithins (up to 100 % acetone-insoluble) to 5,0 g with blank soybean oil and then to 10 g with 1-butanol. Mix the samples on a tilt table mixer for 1 h and then dilute 1:10 with 1:1 blank oil/1-butanol to give a total dilution of 1:500. 10 Calculation Computation is a feature of most instrument programs. Area counts from known standards are inserted into a linear regression formula. From this relationship, concentrations may be determined from the area counts of the samples. It is important to include the correct dilution factor. 11 Precision 11.1 Interlaboratory test Details of interlaboratory tests on the precision of the method are summarized in Annex A. The values derived from these interlaboratory tests may not be applicable to concentration ranges and matrices other than those given. 11.2 Repeatability The absolute difference between two independent single test results, obtained with the same method on identical test material in the same laboratory by the same operator using the same equipment within a short interval of time, will in not more than 5 % of cases be greater than the repeatability limit (r) as shown in Annex A. 11.3 Reproducibility The absolute difference between two single test results, obtained with the same method on identical test material in different laboratories with different operators using different equipment, will in not more than 5 % of cases be greater than the reproducibility limit (R) as shown in Annex A. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/22/2007 08:16:36 MDTNo repr