SIST EN 16424:2015

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Charakterisierung von Abfällen - Screening-Verfahren zur Bestimmung der elementaren Zusammensetzung mit tragbaren RöntgenfluoreszenzspektrometernCaractérisation des déchets - Méthode de dépistage pour la détermination de la composition élémentaire au moyen d'analyseurs portables de fluorescence XCharacterization of waste - Screening methods for the element composition by portable X-ray fluorescence intruments13.030.01Odpadki na splošnoWastes in generalICS:Ta slovenski standard je istoveten z:EN 16424:2014SIST EN 16424:2015en,fr,de01-januar-2015SIST EN 16424:2015SLOVENSKI
STANDARD



SIST EN 16424:2015



EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16424
October 2014 ICS 13.030.01 English Version
Characterization of waste - Screening methods for the element composition by portable X-ray fluorescence instruments
Caractérisation des déchets - Méthode de dépistage pour la détermination de la composition élémentaire au moyen d'analyseurs portables de fluorescence X
Charakterisierung von Abfällen - Screening-Verfahren zur Bestimmung der elementaren Zusammensetzung mit tragbaren Röntgenfluoreszenzspektrometern This European Standard was approved by CEN on 16 August 2014.
CEN members are bound to comply with the CEN/CENELEC 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 Centre 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 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, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16424:2014 ESIST EN 16424:2015



EN 16424:2014 (E) 2 Contents Page Foreword .4 1 Scope .5 2 Normative references .5 3 Terms and definitions .5 4 Principle .5 5 Safety remarks .6 6 Apparatus and equipment .6 6.1 X-ray fluorescence spectrometer .6 6.2 Direct measurement using a hand-held instrumentation in direct contact with the sample .7 6.3 Hand-held instrumentation mounted on a stand using sample cups filled with the sample .7 6.4 Portable bench top XRF instrument .7 6.5 Spoon, stamp and/or hammer .7 6.6 Mortar and pestle .7 6.7 Thin-film support .7 6.8 Sample cups .7 7 Calibration .7 7.1 General .7 7.2 Interferences .8 7.3 Calibration procedure .8 7.4 Validation of the calibration .8 8 Screening strategy. 10 9 Sample preparation . 12 9.1 General . 12 9.2 Sample preparation for direct measurement . 12 9.3 Sample preparation for filling cups . 12 9.4 Sample preparation for heterogeneous samples . 12 10 Analysis . 12 10.1 General . 12 10.2 Direct in situ measurement (hand-held method) . 12 10.3 Measurement by using a mounted hand-held XRF instrument or a small portable closed XRF instrument . 13 11 Calculation of the result . 13 12 Assessment of the XRF screening measurement . 13 12.1 General . 13 12.2 Identification of the presence or absence of the elements under investigation . 13 12.3 Indication of the concentration range of the elements under investigation . 14 13 Quality control . 14 13.1 Drift correction procedure . 14 13.2 Blank test . 14 13.3 Reference materials . 14 14 Test report . 15 Annex A (informative)
Examples of instrumentation . 16 Annex B (informative)
List of analytical lines and spectral line overlaps . 18 SIST EN 16424:2015



EN 16424:2014 (E) 3 Annex C (informative)
Evaluation of the acceptance criteria . 19 C.1 Uncertainty . 19 C.2 Test of the absence of an element . 19 C.3 Test of the documented concentration of an element . 19 C.4 Estimation of uncertainty . 20 Annex D (informative)
Validation . 21 Bibliography . 32
SIST EN 16424:2015



EN 16424:2014 (E) 4 Foreword This document (EN 16424:2014) has been prepared by Technical Committee CEN/TC 292 “Characterization of waste”, 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 April 2015, and conflicting national standards shall be withdrawn at the latest by April 2015. 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. X-ray fluorescence spectrometry (XRF) is a fast and reliable method for the determination of the total content of certain elements within different matrices. Quantitative analysis using XRF is described in EN 15309 [2]. For screening purposes, portable instruments are often used, especially when only the absence or presence of elements is under investigation or qualitative results with an indication of the concentration level are requested. This standard is applicable for on-site verification at landfills (see CEN/TR 16130 [4]) and it is an exemplification of EN 16123 [3]. According to the CEN-CENELEC Internal 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, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16424:2015



EN 16424:2014 (E) 5 1 Scope This European Standard is dedicated to field portable X-ray fluorescence (XRF) equipment (hand-held or portable bench top) and specifies a screening method for the determination of the elemental composition of waste materials for on-site verification. Portable XRF spectrometers are used for a rapid and exploratory analysis of paste-like or solid materials. The absence or presence of specific elements is displayed qualitatively with an indication of the concentration level. 2 Normative references The 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, the latest edition of the referenced document (including any amendments) applies. EN 15002, Characterization of waste — Preparation of test portions from the laboratory sample 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 field portable XRF spectrometer XRF spectrometer for analyzing samples in the field, namely hand-held or portable bench top XRF spectrometers 3.2 hand-held XRF spectrometer XRF spectrometer which can be used for in-situ analysis by direct probing or mounted on a stand 3.3 on-site verification third level of inspection according to the Landfill Directive and the Landfill Decision to ensure that the waste accepted at a landfill is the same as described in the accompanying documents and that it is in accordance with the basic characterization and/or compliance testing 3.4 portable bench top spectrometer compact bench top XRF spectrometer which can easily be carried into the field 3.5 screening application of any analytical method for exploratory analysis 4 Principle The sample can be measured directly or after a suitable sample preparation. In principle two different methods are used for probing the sample, either a pistol-like instrument is placed directly on the sample or a sufficient test portion is taken and put into a sample cup for measurement with the XRF instrument. The presence of a specific element is verified if a significant intensity for that element is measured. The intensities of the lines can be evaluated to indicate the concentration range. SIST EN 16424:2015



EN 16424:2014 (E) 6 5 Safety remarks The X-ray fluorescence spectrometers on the market are generally fully protected apparatus which are subjected to specific official approval and acceptance conditions. This means that the user is not exposed to radiation when operating the apparatus correctly. Nevertheless while measuring in the field, scattering radiation can be produced when probing directly on the sample. Providing a protective radiation shield around the sample when measuring avoids these risks. The person responsible for managing or supervising the operation of X-ray equipment shall provide evidence of his knowledge of radiation protection according to national regulations. Proper safety precautions shall be considered when conducting field XRF measurements. The operator should always be aware that X-rays are produced during measurements. The operator should never point the open source at anyone and be aware that X-rays can penetrate through light atomic mass matrices. Proper training regarding handling of XRF instruments is an obligation. Take care when handling samples that may contain sharps or are of a dusty nature. Handling of samples should be performed with gloves and in the case of dusty materials with respiratory mask and gloves. Take special precautions with samples from potentially hazardous waste. Avoid any contact with the skin and/or inhaling of dust. 6 Apparatus and equipment 6.1 X-ray fluorescence spectrometer The X-ray fluorescence spectrometer shall comply with European and national regulations relevant to radiation protection. The X-ray fluorescence spectrometer shall be able to analyse the relevant elements. The following types of X-ray fluorescence spectrometers are applicable: — energy dispersive X-ray fluorescence spectrometer (EDXRF) which gains the dispersion of the emitted X-ray fluorescence radiation by an energy dispersive detector; — wavelength dispersive X-ray fluorescence spectrometer (WDXRF) which gains the dispersion of the emitted X-ray fluorescence radiation by diffraction by a crystal. For screening analysis generally EDXRF instruments are applied. Portable spectrometers comprise mainly the following components: — a primary X-ray source, a miniaturised X-ray tube with a low voltage generator; — a detector unit including electronic equipment; — a power supply including rechargeable batteries; — a radiation shield according to safety regulations; — optional source modifiers to modify the shape or intensity of the source spectrum or the beam shape e.g. primary source filters. Portable spectrometers are mostly hand-held instruments which may be mounted on a stand. Alternatively small bench top systems are available which are equipped with a sample holder. In general, the weight of portable instruments should be below 10 kg and the size should be less than 500 mm wide, 500 mm deep and 200 mm high. SIST EN 16424:2015



EN 16424:2014 (E) 7 The detector unit is different for wavelength dispersive (WDXRF) and for energy dispersive (EDXRF) spectrometers. WDXRF spectrometers take advantage of the dispersion of the emitted radiation by scattering by a crystal. EDXRF spectrometers are using an energy dispersive detector. The detector current pulses, a measure for the energy of the incoming X-rays, are segregated into channels according to energy using a multi-channel analyser (MCA). 6.2 Direct measurement using a hand-held instrumentation in direct contact with the sample When using a pistol-like instrument, direct probing of the sample is possible (see Figure A.1 and Figure A.2). To avoid uncertainties due to different measurement geometry such as distance to sample, angle between sample and incident beam, the measuring window of the instrument should be in close contact to the sample. 6.3 Hand-held instrumentation mounted on a stand using sample cups filled with the sample For practical reasons or to improve the accuracy of the results due to different measurement geometries, hand-held instruments may be mounted in a stand to operate with a well-defined geometry. Sample cups containing the material under investigation are placed into the instrument at a fixed position (see Figure A.3 and Figure A.4). 6.4 Portable bench top XRF instrument Portable bench top XRF systems equipped with a sample holder for positioning sample cups may show improved repeatability of the results compared to hand-held instruments. A mounted shield against X-ray radiation provides a higher safety protection (see Figure A.5). 6.5 Spoon, stamp and/or hammer Tool to prepare (e.g. compress, flatten) the sample prior to the measurement. 6.6 Mortar and pestle Tool to grind the sample, if required. 6.7 Thin-film support Select a thin film support that provides maximum transmittance and is resistant to the components in the sample (e.g. Mylar, polypropylene). Preferably samples are analysed using the same film that was previously used for calibration. The selected thin film shall be contaminant-free with respect to the elements of interest. 6.8 Sample cups Select a sample cup suitable to be positioned in the applied XRF system. The sample cup needs to be assembled using an appropriate thin film support. 7 Calibration 7.1 General The calibration strategy is comparable for energy dispersive and wavelength dispersive technique. When using energy dispersive instruments, deconvolution of the spectra is needed when analysing complex samples with overlapping lines. Usually XRF instruments are supplied with a specific software module for that purpose. SIST EN 16424:2015



EN 16424:2014 (E) 8 The calibration procedures for screening purposes are dependent on the analytical software package of the instrument. Most of them use a programme which contain calibration curves previously set-up; often by the manufacturer. In most cases the user can also set-up calibration programmes or improve the existing ones. 7.2 Interferences Interferences in X-ray fluorescence spectrometry consists of spectral line overlaps, matrix effects, spectral artefacts and particle size or mineralogical effects. Spectral line overlaps occur when an analytical line cannot be resolved from the line of a different element. In general, these interferences are removed using the algorithms provided with the software. However, due to the complexity of waste samples optimal matrix calibration is in most cases not affordable for screening experiments. Therefore the user shall be aware of those characteristic interferences which may occur in waste samples under investigation. A list of characteristic interferences is given in Annex B. Matrix effects occur when the X-ray fluorescence radiation from the analyte element is absorbed or enhanced by other elements in the sample before it reaches the detector. Spectral artefacts (e.g. escape peaks, sum peaks, pulse pile up lines, dead time, bremsstrahlung correction) are accounted for by the provided software. Spectral artefacts differ for energy-dispersive and wavelength-dispersive XRF. 7.3 Calibration procedure Calibration involves the measurement of emitted intensities of characteristic lines for specimens of known composition. The basic formula implies a linear relationship between the intensity and the concentration. ii,0i,1i=+×CaaI (1) where iC is the concentration of the element of interest; i,0a is the offset of the calibration curve; i,1a is the slope of the calibration curve; iI is the net intensity of the element of interest. Different calibration procedures can be applied for the determination of the element concentration according to EN 15309 [2]. It is a necessity to select a calibration programme which is able to handle the sample matrices under investigation, meaning performing the deconvolution, the interelement corrections and the calculation of the element concentration in a proper way. This can be done by using a universal or matrix-specific calibration programme. It is the task of the XRF user to validate the system with representative reference samples. 7.4 Validation of the calibration The calibration shall fit with the concentration values to be verified by the investigation. The calibration protocol should be able to verify the lowest (highest) values within the calibration range. The available precalibrated analytical method shall be validated using reference materials with a similar composition as the unknown samples. Based on the obtained results an estimation of the uncertainty range for each analyte can be defined. The reference sample can consist of: a) certified reference materials with matrices similar to that of the unknown sample; SIST EN 16424:2015



EN 16424:2014 (E) 9 b) in-house made reference materials with matrices similar to that of the unknown sample; c) synthetic standard samples, made by weighing the appropriate amount of each pure reagent; d) site specific or batch specific samples, similar to the matrix of the unknown sample; e) standard addition method or spiked samples may also be used to create standards for which appropriate reference materials are not available for an element of interest; the matrix material shall match that of the unknown sample. The element concentrations of these reference samples shall be known, by certification, or by determination with another analytical technique. The reference materials shall be analysed under the same analytical conditions as the unknown sample, meaning the same sample preparation (pellet, powder, etc.), the same analytical measurement method, etc. If no reference materials with a comparable matrix as the unknown sample are available, only a qualitative analysis with indicative concentration values can be performed. A method can be defined as (semi)-quantitative when the uncertainty ranges can be defined. SIST EN 16424:2015



EN 16424:2014 (E) 10 8 Screening strategy The operational steps for screening experiments are defined below and presented in the flowchart in Figure 1. Step 1: Define analytical task. Identify the elements including the corresponding concentration values to be verified and/or decision values.
Elements of interest are listed in the European and national legislation. In case of landfills the European Landfill Directive mentions these elements as relevant: As, Ba, Cd, Cr, Cu, Hg, Mo, Ni, Pb, Sb, Se, Zn, (Cl). Step 2: Perform the necessary sample preparation.
The sample preparation technique depends on the selected measurement procedure. See Clause 9. Step 3: Select a suitable (matrix specific) XRF calibration programme (see Clause 7). Step 4: Perform the replicate measurements (see Clause 10) and calculate the relative repeatability standard deviation (Vr) of the replicates. Step 5: Is Vr of the replicates sufficiently low? If no, go to step 6; if yes, continue with Step 7.
When evaluating the resulting concentration values, the Vr in relation with the concentrations to be verified and/or decision values shall be considered.
Usually a Vr of less than 30 % is a proper criterion to decide between acceptable or not acceptable results. Step 6: If Vr is not sufficiently low, the sample preparation needs to be improved. Check, if the results are getting acceptable by repeated sample preparation. If yes, repeat from step 2. If no, go to Step 12.
Improved sample preparation can include homogenization, and drying. Step 7: Is an indication of the concentration level required? If no, go to Step 8; if yes, continue with Step 10. Step 8: Compare the mean of the results with the limit of detection (LOD) (see 12.2). Step 9: Indicate the absence or presence of the elements under investigation with respect to the set limit values (see 12.2). Step 10: Identify the acceptance criteria (see 12.3). Step 11: Report the elements under investigation and indicate their concentration ranges. Step 12: XRF screening is not suitable. Stop experiment.
SIST EN 16424:2015



EN 16424:2014 (E) 11
Figure 1 — Flowchart of the operational steps for screening experiments SIST EN 16424:2015



EN 16424:2014 (E) 12 9 Sample preparation 9.1 General Milling and sieving are usually not applied because screening methods are used to obtain a preliminary result without or at least with limited sample preparation. Nevertheless in many cases the samples under investigation are very heterogeneous. Because XRF is a surface analysis technique, any sample preparation can improve the reliability of the results. The principles of EN 15002 shall be considered. Be aware that the sample conditions, for example moisture content, organic content, particle size, high contents of some elements, have a significant influence on the quality of the results. 9.2 Sample preparation for direct measurement In case of direct measurement (see 6.2) it is recommended to flatten and to compress the sample spot before measurement. 9.3 Sample preparation for filling cups Sample cups provided with a suitable thin film foil are properly filled with sample material (as representative as possible) so that the bottom is completely covered. The material is shaken so that fine and coarse material are similarly distributed in the bottom of the cup. Use a spoon or a stamp to press the material tightly. Prepare at least three similar test samples from each sample spot. 9.4 Sample preparation for heterogeneous samples Heterogeneous samples need further sample pretreatment if qualitative results with an indication of the concentration level are required. Drying of the collected sample and/or grinding of these sample using mortar and pestle might improve the quality of the results. Heterogeneity is identified by high standard deviation values of the replicates (see Clause 8). The moisture content of the sample has also an influence on the calculation of the concentration. The estimated value may be based on the wet sample. 10 Analysis 10.1 General Follow the instrument manufacturer’s instructions for set-up, conditioning, preparation and maintenance of the XRF spectrometer. Each XRF instrument should be operated according to the manufacturer’s recommendations. Before analysis, quality control samples shall be measured to check the instrument stability and the quality of the calibration in accordance to the manufacturer’s instructions. Select the proper calibration programme. 10.2 Direct in situ measurement (hand-held method) Direct the X-ray probe to the sample, measure the sample and record the data (see 6.2). Repeat the procedure at least 3 times, preferably 5, on different spots. Evaluate the recorded data, calculate the relative repeatability standard deviation (Vr) and perform the assessment of the XRF screening experiment according to Clause 12. SIST EN 16424:2015



EN 16424:2014 (E) 13 NOTE Measurement time commonly used varies between 30 s and 90 s for each measurement. 10.3 Measurement by using a mounted hand-held XRF instrument or a small portable closed XRF instrument Instead of measuring in situ, samples can be collected and placed into a sample cup. Either a hand-held instrument mounted on a stand (see 6.3) or a small portable bench top instrument (see 6.4) can be used. In case of a bench top system introduce the filled sample cup into the sample holder. In case of a mounted hand-held instrument place the sample cup in front of the X-ray window at a fixed position according to the technical notes of the instrument supplier. Measure the sample and record the data. Repeat the procedure at least 3, preferably 5, times by collecting samples from different spots. Evaluate the recorded data, calculate the relative repeatability standard deviation (Vr) and perform the assessment of the XRF screening experiment according to Clause 12. NOTE Measurement time commonly used varies between 30 s and 90 s for each measurement. 11 Calculation of the result The concentrations of the analytes are calculated by the software programme from the measured intensit
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