1、BSI Standards PublicationBS EN ISO 17184:2014Soil quality Determinationof carbon and nitrogen bynear-infrared spectrometry(NIRS)BS EN ISO 17184:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO 17184:2014.The UK participation in its preparation was entrus
2、ted to Technical Committee EH/4, Soil quality.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Stan
3、dards Institution 2014.Published by BSI Standards Limited 2014ISBN 978 0 580 76248 2ICS 13.080.10Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2014.Ame
4、ndments/corrigenda issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 17184 May 2014 ICS 13.080.10 English Version Soil quality - Determination of carbon and nitrogen by near-infrared spectrometry (NIRS) (ISO 17184:2014) Qualit du sol - Dosage du carbo
5、ne et de lazote par spectromtrie proche infrarouge (SPIR) (ISO 17184:2014)Bodenbeschaffenheit - Bestimmung von Kohlenstoff und Stickstoff durch Nahinfrarotspektroskopie (NIRS) (ISO 17184:2014) This European Standard was approved by CEN on 24 April 2014. CEN members are bound to comply with the CEN/C
6、ENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centr
7、e or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the
8、official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherla
9、nds, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2014 CEN All rights
10、 of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 17184:2014 EBS EN ISO 17184:2014EN ISO 17184:2014 (E) 3 Foreword This document (EN ISO 17184:2014) has been prepared by Technical Committee ISO/TC 190 “Soil quality” in collaboration with Techn
11、ical Committee CEN/TC 345 “Characterization of soils” the secretariat of which is held by NEN. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by November 2014, and conflicting national standards sha
12、ll be withdrawn at the latest by November 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal
13、Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Irelan
14、d, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 17184:2014 has been approved by CEN as EN ISO 17184:2014 without any modification. BS EN I
15、SO 17184:2014ISO 17184:2014(E) ISO 2014 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative references 13 Principle 14 Apparatus . 15 Procedure. 25.1 Preparation of samples 25.2 Instrument calibration . 25.3 Sample measurement 46 Test report . 5Annex A (informative) Precision data
16、. 6Bibliography 9BS EN ISO 17184:2014ISO 17184:2014(E)ForewordISO (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. E
17、ach 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 Internati
18、onal Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the differen
19、t types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall no
20、t be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is inf
21、ormation given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see
22、the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 190, Soil quality, Subcommittee SC 3, Chemical methods and soil characteristics.iv ISO 2014 All rights reservedBS EN ISO 17184:2014INTERNATIONAL STANDARD ISO 17184:2014(E)Soil quality Determi
23、nation of carbon and nitrogen by near-infrared spectrometry (NIRS)1 ScopeThis International Standard specifies a method for the determination of carbon and nitrogen in soils by direct measurement of sample spectra in the near-infrared spectral region. The spectra are evaluated by a suitable calibrat
24、ion model derived from the results obtained by reference methods.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, th
25、e latest edition of the referenced document (including any amendments) applies.ISO 11464, Soil quality Pretreatment of samples for physico-chemical analysis3 PrincipleSoil samples are measured by reflectance near-infrared (NIR) spectroscopy. Diffuse reflectance NIR spectroscopy offers a non-destruct
26、ive means for measurement of soil properties based on reflectance spectra of illuminated soils. Spectral data are evaluated by a suitable calibrating model derived from the measurement of a sufficient number of representative soil samples with known content of carbon and/or nitrogen determined by re
27、ference methods. Calibration equations reflect the relationship between the constituents of the sample and NIR spectral information. The soil samples and the set of calibrating samples for the NIR measurement are prepared the same way.NOTE 1 NIR spectrometry is a very fast non-destructive and enviro
28、nmentally friendly analytical technique when compared to the standard chemical methods used as reference methods.NOTE 2 Soils generally have similar reflectance spectra in the 1 100 nm to 2 500 nm range. The absorption peaks for soils in the near-infrared region are difficult to assign to specific c
29、hemical components.4 Apparatus4.1 Near-infrared instrument, based on measurement of reflectance spectra in the near-infrared region (wavelength range from 900 nm to 2 500 nm is usually applied). The instrument should be equipped with a suitable measurement cell for pulverized solid samples. The inst
30、rument should measure sufficiently large sample volume to eliminate any significant influence of inhomogeneity of the sample. The software shall allow instrument tests, calibration, sample measurement and data evaluation.Resolution of the instrument should be equal to 8 nm or better.NOTE Wavelengths
31、 of spectra recorded in higher resolution may be averaged to reduce spectra noise and there is a risk of over fitting of the calibration model. Instruments with lower resolution may be used if their performance is verified for intended purposes. ISO 2014 All rights reserved 1BS EN ISO 17184:2014ISO
32、17184:2014(E)5 Procedure5.1 Preparation of samplesSoil samples shall be prepared the same way as soils used for the instrument calibration. Any difference in sample preparation may influence the measurement. Sample preparation shall ensure a good homogenization of the sample.Sample preparation accor
33、ding to ISO 11464, particle size 2 mm, is generally used. Air-dried or oven-dried samples can be used for analysis. The method is not suitable for samples with water content higher than 10 %. Oven drying is recommended for samples with high specific surface area that are susceptible to changes in wa
34、ter content due to fluctuations in air humidity.5.2 Instrument calibration5.2.1 GeneralA suitable set of uniformly prepared soil samples is measured by NIR spectroscopy. The spectra and the results of the content of carbon and/or nitrogen determined by a reference method are used for calculation of
35、the calibration model. Calibration should include enough samples to cover most of the possible spectral variability encountered during routine analysis and to predict the composition of unknown samples accurately. The calibration sample set shall be selected to gain an evenly distributed coverage of
36、 the property range.The NIR spectra represent cumulative information about the chemical and physical properties of a sample. Influence of physical properties of a sample (e.g. particle size), is reduced by mathematical corrections as derivatives, standard normal variate (SNV), multiplicative scatter
37、 corrections (MSC), etc. There are several possible ways for development of calibration equations and no specific procedure can be given. The choice shall aim at minimising the calibration error. The methods most frequently applied in the development of calibration equations are: PCR (principal comp
38、onent regression), PLS (partial least square regression), LWR (locally weighted regression), SMLR (stepwise multiple linear regression) and ANN (artificial neural network regression). Among these methods, only ANN methods can give calibration for the whole concentration range for carbon and nitrogen
39、 in soils but ANN methods only apply with more than 500 calibration samples. For other statistical methods, splitting of the concentration range into two calibrations was found to be the best solution. Removal of outliers from the calibration set usually reduces the robustness of the calibration and
40、 should be avoided.For samples from different locations and soil types, a minimum of 60 to 100 calibration samples is required. A smaller number of calibration samples can be used for sample sets with lower variability such as samples from a defined location.NOTE 1 Transformations of the reference m
41、easurements or the spectra using e.g. log or square root transformed reference measurements may help to reduce the calibration error.NOTE 2 It is possible that calibrations developed on a certain instrument may not always be transferred directly to an identical instrument. It may be necessary to per
42、form bias and slope adjustments to calibration equations. In many cases it is necessary to standardize the two instruments against each other before calibration equations can be transferred. Standardization procedures can be used to transfer calibrations between instruments of different types provid
43、ed that samples are measured the same way and that the spectral region is identical.NOTE 3 If the reference method is unbiased and a good linear calibration model is achieved, increasing number of calibration samples averages out errors in the reference method. Therefore, the lack of repeatability i
44、n the reference method can be compensated for by using high number of calibrating samples.2 ISO 2014 All rights reservedBS EN ISO 17184:2014ISO 17184:2014(E)5.2.2 Validation of the calibration model5.2.2.1 GeneralThere are two main methods for validation of the calibration model: cross (internal) va
45、lidation (see 5.2.2.2), and external validation (see 5.2.2.3).Cross validation (see 5.2.2.2) is used to determine the number of factors used for PLS by determining a minimum RMSECV (root mean square error of cross validation), and when not enough samples are available for external validation. The nu
46、mber of factors shall be as small as possible to avoid over fitting of the calibration model. An external validation (see 5.2.2.3) shall be used to determine the calibration error since cross validations tend to underestimate the calibration error.In all cases, if a new calibration is developed on a
47、n expanded calibration set, the validation process should be repeated. The calibrations should be checked whenever any major part of the instrument (optical system, detector) has been changed or repaired.Next to the initial validation, NIR calibrations should be validated on a regular basis against
48、reference methods to ensure optimal performance of calibrations. The frequency of checkings depends mainly on the number of changes in the sample population. The number of samples for the continuous checking should be sufficient for the statistics applied. The validation exercise is valid only for t
49、he range and for the sample types used in the validation.The prediction ability of the calibration model is given by the correlation coefficient (R) and the root mean squared error of prediction (RMSEP) which is also called root mean squared error of cross validation (RMSECV) when using cross validation. These characteristics should be reported with the results. If the difference between two parallel measurements is higher than RMSECV or RMSEP, the results may not be valid and should be investigated further.5.2.2.2 Cross validationThe set of calibration dat
