VALIDATION REPORT. Investigation of the major interferences for proposed Horizontal ICP AES method. ECN protocol

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1 Page 1 van 36 pages VALIDATION REPORT Investigation of the major interferences for proposed Horizontal ICP AES method Identification code Validation in accordance with Reference method Scope Reference number SOP Instrument Method description Validation type V04101 ECN protocol Horizontal WP6 no 19 ICP-AES Soil, Sludge, Biowaste W6404 Perkin Elmer 4300 DV ICP-AES DL and Robustness Name Signature Date Validation study carried out by Validation report approved by Lab manager Validation report approved by QA

2 Page 2 van 36 pages 1 INTRODUCTION The main objective of the Horizontal program is the development of horizontal and harmonized European standards in the fields of the analysis of sewage sludge, soil, contaminated soil and treated bio-wastes to facilitate regulation of these major streams in the light of the different uses and disposal options that are governed by EU Directives. The goal of this study is [from 7.1]: Investigation of the major interferences to common elements and digested samples of matrices and digests in question are investigated for the ICP-AES method. Emphasis is given to interferences corrections and quality control criteria related to interferences and matrix effects. The basis for this study is the Horizontal WP6-19 document: Determination of elements by ICP-AES and ICP-MS, may 2004 by Henk J. van de Wiel, Annex 2: STANDARD HORIZONTAL ICP_AES METHOD[7.2]. Within Horizontal there are two proposed methods for digestion of samples. As both methods are being developed in a concurrent study, this study is carried out in Aqua Regia and nitric acid digests according to the digestion described in Horizontal WP6 18 (may 2004)[7.3]. A work definition for the determination of the Instrumental Detection Limit (IDL) is defined and the definition for MDL of a Dutch standard (NEN 7777) is used [7.4]. 1.1 Scope The experimental work in this study will be performed on a PE Optima 4300 DV instrument. The set up for the determination of the DL and the interferences are based on routine multi-element conditions and according to the settings proposed by the STANDARD HORIZONTAL ICP_AES METHOD[7.2]. The matrices under investigation in this study are digests from the matrices which are stated in table 1. Table 1: Matrices used in this study Soil Sludge (treated) Bio waste In of the scope of H-19 ICP-AES? Yes Yes Yes The project description mentions common elements in its scope. The elements selected for this study are given in table 2. Besides these elements the matrix elements which can be expected in environmental samples, like Al, Ca, Mg, Fe, C, Na and K are also part of the scope but not part of the QC and related interferences investigations. Table 2:

3 Page 3 van 36 pages Elements used in this study CAS-number Part of the scope of H-19 ICP-AES? Arsenic (As) Yes Cadmium (Cd) Yes Chromium (Cr) Yes Copper (Cu) Yes Lead (Pb) Yes Nickel (Ni) Yes Zinc (Zn) Yes Antimony (Sb) Yes Barium (Ba) Yes Beryllium (Be) Yes Cobalt (Co) Yes Molybdenum (Mo) Yes Selenium (Se) Yes Silver (Ag) Yes Thallium (Tl) Yes Tin (Sn) Yes Vanadium (V) Yes 1.2 Summary of method The method describes the multi-elemental determination of elements by simultaneous optical ICP-AES with axial or radial viewing of the plasma in aqueous and nitric of aqua regia digests. The instrument measures characteristics emission spectra by optical spectrometry. Samples are nebulized and the resulting aerosol is transported to the plasma torch. Element-specific emission spectra are produced by radio frequency inductively coupled plasma. The spectra are dispersed by a grating spectrometer, and the intensities of the emission lines are monitored by photosensitive devices. Background correction is required for trace element determination. Background correction is not required in cases of line broadening where background correction measurement would be actually degrading the analytical result. Additional interferences and matrix effects must be recognized and appropriate corrections made. Test for their presence are described. Alternatively, users may choose multivariate calibration methods. In this case, point selections for background correction are superfluous since whole spectral regions are processed.

4 Page 4 van 36 pages 1.3 Definitions For this study the following definitions are applied. Instrumental limit of detection (IDL): 3 * S r (the standard deviation calculated from multiple readings (n=10) of a blank within a single run). Method limit of detection (MDL): 3 *S r (the standard deviation calculated from multiple measurements (n> 8 ) of a matrix solution with low analyte concentration ). 2 INSTRUMENTATION A Perkin Elmer Optima 4300 DV (where DV stands for Dual(axial and radial) View) instrument is used for this study. 2.1 Apparatus. A Perkin Elmer Optima 4300 DV with a PE sharp cone spray is used according to the requirements stated in 6.2 of the proposed standard. Acquisition software is used for data acquisition and reprocessing and a Cetac ASX 510 autosampler for sample introduction. The instrument has been set up in multi element mode for the elements given in table 2. The instrument is tuned as required by the manufacturer. A Multiwave 3000 microwave (Anton Paar, Austria) with HF100 digestion vessels is used for digestion. 2.2 Reagents All reagents used are of PA or Baker analyzed quality. 2.3 Standards BDH multi element Standard solution (cat no W) Perkin Elmer Tellurium standard solution (cat no N ) Pure element standards (Baker Instra Analyzed and Perkin Elmer Pure ) C element = [1000 mg/l]. Four internal standards(y, Rh (I+II), In (I+II)) are used which are added to all solutions.

5 Page 5 van 36 pages 3 PROCEDURES 3.1 Method development A method will be develop for multi element measurement of the elements given in table 1 and matrix elements in accordance with the manufacturer s manual. As the instrument is Dual View both directions will be part of the method although not all will be useful. The wavelength for measurement and background subtraction will be determined. A wavelength check and calibration is part of the daily performance test. The adjustment of the wavelength is performed by the service engineer during PM. 3.2 Interferences (from matrix) Digests from the matrices specified in table 1 will be analyzed and relevant concentrations of the major matrix elements determined. For this purpose several available Certified Reference Materials will be digested in aqua regia and nitric acid and analyzed with the method developed in 3.1: 1. CRM 145R: sewage sludge. 2. FeNeLab: internal reference material, river clay. 3. Lksd-1: lake sediment. 4. Stsd-2: stream sediment. 5. CRM 7001: light sandy soil. 6. CRM 144R: sewage sludge from domestic origin. 7. CRM 141R: Calcareous loam soil. 8. AMB WB: internal reference material: lake sediment. 9. AMB SZ: internal reference material: playground sand. 10. AMB Compost: internal reference material; biowaste/garden waste. 3.3 Interference Check Solution (ICS) Based on the composition of relevant matrices and the proposed ICS [7.] content the composition of the ICS will be determined. The content of the ICS will be bases upon the levels obtained at 3.2. The (potentially) interfering elements (see table 1 [7.3]) are quantified and checked against the criterion stated in the proposed standard (less than 5% impact on the measured value or 3 times the Instrumental DL). Interferences which are investigated in this study: Spectral ; Background and stray light.

6 Page 6 van 36 pages 3.4 IEC correction Single element stock solutions are used to determine the major interferences for ICP AES method. From these single element stock solutions a series of nine standard solutions with a concentration of 200 mg/l will be made and measured in 5 separate consecutive runs. The successive values of the correction factor shall not differ more than 20%. Group I Group II Interferent standard I Interferent standard II Interferent standard III Interferent standard IV Interferent standard V Interferent standard VI Interferent standard VII Interferent standard VIII Interferent standard IX V, Al, Ba, Ca, Ce La, Cu, Cd, Co, Cr Fe, Mo, Nd, Ti, Zn Ni, S, As, Mg, Mn V, Ti, Cu Fe, Cr, Nd Mn, Mo Ni, Zn, Nd La, Ce For this experiment standard solutions in diluted nitric acid are aspirated into the plasma and for all elements of interest the possible interference is measured. The Inter- Element-Correction-factors (IEC) are calculated from these measurements. The IEC used in this study are the average of 5 measurements. Beside the measurement of the IEC the background correction profile is optimized by measuring the ICS solution and evaluation of the interference by other lines caused by elements present in the ICS. Non spectral interferences (like physical, chemical and memory effects) are not investigated in this study. The effect of these interferences is minimized by the use of an internal standard and through matrix matching. The following internal standards and their emission lines are examined: Yttrium (ion line) Rhodium (atom line) Rhodium (ion line) Indium (ion line) Indium (atom line) 3.5 Detection Limit in matrix solution (ICS) The instrumental and method limit of detection limit are determined according to the definitions in 1.3. The content of the ICS used for this purpose depends on the result of ICS in 3.2 & 3.3. The obtained values are expressed is solution concentration (mg/l) of the digest. Therefore the detection limit is also expressed in mass concentration after recalculation with an amount of 2.5g soil, filled to the end volume of 100 ml. 3.6 Precision

7 Page 7 van 36 pages Within the scope of this study the precision is defined as the relative standard deviation of the reproducibility of digests of relevant samples. Digests of the CRM s are measured on different days. The within laboratory reproducibility standard deviation (S W ) is calculated. 3.7 Recovery of spike The recovery is investigated with two different methods which are both mentioned in the proposed standard. The first is a spike to a matrix solution (ICS) and the second is the ratio of measurements of the original sample and a diluted sample. The post-digestion spike recovery shall be between 80 and 120% or the difference between results for nondiluted and the fivefold diluted sample shall be less than 20%.

8 Page 8 van 36 pages 4 RESULTS 4.1 Method development The method is developed according to guidelines given in the proposed standard [7.2]. For a description of the method applied see annex 6.1: Element view Emission wavelength (nm) Ag, Silver Axial As, Arsenic Axial (1 Ba, Barium Radial Be, Beryllium Axial Cd, Cadmium Axial Co, Cobalt Axial Cr, Chrome Axial Cu, Copper Axial Mo, Molybdenum Axial Ni, Nickel Axial Pb, Lead Axial Sb, Antimony Axial Se, Selenium Axial Sn, Tin Axial ( ( Tl, Thallium (3 Axial V, Vanadium Radial Zn, Zink Radial Remarks: (1 The in the Standard Horizontal method ICP-AES [4.1] given emission wavelength for Arsenic of nm is not available on the Optima 4300 DV. There is a chance that the available wavelength at is the same. The establishment of emission wavelengths happened in the past by using spectrophotometers with a much lower resolution then the modern ones. (2 In the Standard Horizontal method ICP-AES [4.1] there is an emission wavelength mentioned for tin of nm which is incorrect and should be nm. (3 The mentioned emission wavelength for thallium in Standard Horizontal method ICP-AES [4.1] of nm is not available on the Optima 4300 DV. 4.2 Interferences The reference materials used in this investigation of the major matrix interferences. 1. CRM 145R: sewage sludge. 2. FeNeLab: internal reference material, river clay. 3. Lksd-1: lake sediment. 4. Stsd-2: stream sediment. 5. CRM 7001: light sandy soil. 6. CRM 144R: sewage sludge from domestic origin. 7. CRM 141R: Calcareous loam soil. 8. AMB WB: internal reference material: lake sediment. 9. AMB SZ: internal reference material: playground sand. 10. AMB Compost: internal reference material; bio waste/garden waste. The reference materials were digested with aqua regia and 1:1 nitric acid as prescribed in the proposed Horizontal standard on digestion [7.3]. The digests are analyzed to

9 Page 9 van 36 pages determine the matrix. The results are summarized in figure 1 Aqua regia and figure 2 for Nitric acid. Figure 1: Aqua regia results Aqua regia digest Content [mg/kg] Blanco_KW TCRM145R_KW T _KW TLKSD-1_KW TSTSD-2_KW TCRM7001_KW TCRM144R_KW TCRM141_KW TAMBWaterb_KW TAMBSpeelz_KW TAMBCompost_KW TAMBCompost_KW TAMBWaterb_KW Ag Al As B_ Ba Be Ca Cd Ce Co Cr Cu Fe La Mg Mn Mo Nd Ni P_ Pb S_ Sb Se Sm Sn Sr Ti Tl V_ Zn TCRM144R_KW TSTSD-2_KW T _KW Blanco_KW

10 Page 10 van 36 pages Figure 2: 1:1 Nitric acid results: Nitric acid digest content [mg/kg] Blanco_SP TCRM145R_SP T _SP TLKSD-1_SP TSTSD-2_SP TCRM7001_SP TCRM144R_SP TCRM141_SP TAMBWaterb_SP TAMBSpeelz_SP TAMBCompost_SP TAMBCompost_SP TAMBWaterb_SP TCRM144R_SP TSTSD-2_SP T _SP Blanco_SP Ag Al As B_ Ba Be Ca Cd Ce Co Cr Cu Fe La Mg Mn Mo Nd Ni P_ Pb S_ Sb Se Sm Sn Sr Ti Tl V_ Zn Discussion: The major matrix elements from real samples are sodium, magnesium, aluminium, phosphorus, sulphur, potassium, calcium and iron. There is not a remarkable difference between the Aqua regia digests and the nitric acid digests of real sample for the elements that are reported. ICP-MS data shows a higher carbon concentration in the nitric acid digests. 4.3 ICS solution Based on the results reported in figure 1 and 2, the concentration for the ICS is determined. Table 3: Maximum ICS concentration: Component Aluminium Iron Potassium Sodium Phosphorus Calcium Magnesium Sulphur Manganese Titanium Concentration 1200 mg/l 950 mg/l 2000 mg/l 230 mg/l 150 mg/l 1800 mg/l 320 mg/l 430 mg/l 20 mg/l 60 mg/l

11 Page 11 van 36 pages Discussion: In the note at Of the proposed standard these elements are called ubiquitous elements together with Cr and V; the latter are not found in the samples used here. The concentrations in the table are the highest concentrations found in the samples. The outcome of the measurements in this study reflects therefore a worst case situation. For control purposes the ICS is suitable but not for quantification of the interference correction factor. 4.4 Major interferences in standard solutions. Selected element stock solutions were used to determine the major spectral interferences for ICP AES methods. A series of nine standard solutions were measured in axial and radial view. The Inter-Element Correction (IEC) factors are reported that were calculated from the measurement data and are summarized in table 4. The criteria for the use of a IEC are less than 5% impact on the measured value or less than 3-times the Instrumental DL). A summary of the data is reported in table 4. Only the criterion for the IDL is used. Table 4: Major interferences. Analyte λ (nm)* Interferent IEC factor (%) Co Ti 0.14 Ni Fe Zn Cu 0.65 Pb Fe V Ti 0.14 Zn Ca Co Fe Cu Fe Ni Cr 2.6 Pb Fe 0.16 Sn Fe * minor differences between the wavelength stated in table 1 of the proposed standard and this table can occur due to small adjustments of the detector used. The spectral lines given below prove to be not useful in the matrix due to interference mainly caused by spectral : Silver nm Antimony nm Selenium nm Tin nm Thallium nm In Annex 6.2 the results of the interference measurement are reported.

12 Page 12 van 36 pages Discussion: The two criterions for applying an IEC are totally different and not very practical. Here the criterion absolute contribution is more than 3 time the MDL is used. The IDL is determined in a pure standard solution which leads to very low, not practically relevant values. Therefore the use of the MDL has more relevance. The IEC is determined with pure standard solutions at a certain chosen concentration. The choice is relevant and matrix dependent. If for example a concentration of 200mg/L is used for IEC determination and there is no observed contribution higher than 3 times the DL but samples contain a higher concentration this can lead to a contribution of the interference that may not be ignored. The 5 % rule is not applicable during the interferences measurement but only applies in real samples where matrix is present. In practice during IEC measurements with pure standards, the need for an IEC is determined and will always be applied in real sample measurement. The 5% rule is only practical in relatively high concentration levels Interference correction stability. The interference correction stability is determined by measuring 5 consecutive runs and calculated as the ratio between two runs. The results for the elements of interest are reported in figure 3.

13 Page 13 van 36 pages Figure 3: Interference Correction stability. IEC stability % Al As Ca Cr Co Cu Fe Mg Mn Mo Ni S Ti V Zn Ag atom axial Ag atom axial As atom axial As atom axial Ba ion rad Ba ion rad Ba ion rad Be ion axial Be ion axial Cd atom axial Cd ion axial Cd atom axial Co ion axial Co ion axial Co ion axial Cr ion axial Cr ion axial Cr ion axial Cu atom axial Cu ion axial Ni ion axial Ni ion axial Pb ion axial Pb atom axial Pb atom axial Sb atom axial Sb atom axial Se atom axial Sn ion axial Sn atom axial Tl ion axial Tl atom axial V ion rad V ion rad V ion rad Zn atom rad Zn ion rad As atom axial Ni atom axial Zn ion rad Note: At the top of the graph are the interfering elements and the 5 consecutive measurements; if an interference has been measured than the element of interest can be found in the legend.

14 Page 14 van 36 pages Figure 4: IEC stability as percentage of the previous measurement. IEC stability as ratio of previous reading Interferent As Cr Co Cu Fe Mg Mn Mo Ni Ti V Zn ratio Ag atom axial Ag atom axial As atom axial As atom axial As atom axial Ba ion rad Ba ion rad Ba ion rad Be ion axial Be atom axial Be ion axial Cd atom axial Cd ion axial Cd atom axial Co ion axial Co ion axial Co ion axial Cr ion axial Cr ion axial Cu atom axial Cu atom axial Cu ion axial Mo ion axial Mo ion axial Mo ion axial Ni ion axial Ni ion axial Ni atom axial Pb ion axial Pb atom axial Pb atom axial Sb atom axial Sb atom axial Se atom axial Sn ion axial Sn atom axial Tl ion axial Tl atom axial V ion rad V ion rad V ion rad Zn ion rad Zn atom rad Zn ion rad

15 Page 15 van 36 pages Discussion: Several elements in figure 3 show sloping curves, all of them are atom lines in axial view. This looks like a specific effect related to the axial view angle of several specific elements, probably a drift caused by thermal effects or system contamination although for the same spectral line, different stability curves are found (see line Sn axial atom for Fe, Mo and Zn). Further investigation of this phenomena has to take place in cooperation with the supplier of the instrument. For most elements the stability of the IEC is good and within the 20% deviation from the previous measurement; this is not always achievable at low values of the IEC. 4.5 Instrumental detection limit. The instrumental detection limit is determined with a reagent blank solution that was obtained at 3.2. Each solution is measured with 10 replicates. The standard deviation multiplied by 3 is the detection limit in solution concentration (mg/l). The instrumental detection limit expressed in mass concentration depends on the amount of the soil that s digested and the end volume. Therefore the instrument detection limit expressed in mass content is calculated with an amount of 2.5 g soil to a final solution of 100 ml. The results are summarized in table 6. Table 6 : Instrumental detection limit: IDL in reagent blanc aqua regia mg/l nitric acid mg/l Ag ion axial Ag atom axial Ag atom axial As atom axial As atom axial As atom axial Ba ion Rad Ba ion Rad Ba ion Rad Be atom axial Be ion axial Be ion axial Cd atom axial Cd ion axial Cd atom axial Co ion axial Co ion axial Co ion axial Cr ion axial Cr ion axial Cr ion axial Cu ion axial Cu atom axial Cu atom axial Mo ion axial Mo ion axial

16 Page 16 van 36 pages Mo ion axial Ni ion axial Ni ion axial Ni atom axial Pb atom axial Pb ion axial Pb atom axial Sb atom axial Sb atom axial Se atom axial Sn ion axial Sn atom axial Tl ion axial Tl atom axial V ion rad V ion rad Zn ion rad Zn ion rad Discussion: The IDL are within the expected concentration range and in good comparison with the IDL proposed in the standard. There is a good comparison of the IDL for aqua regia and nitric acid The method for determination of the instrument detection limit is not clear and should for reason of comparison be part of the standard. Method detection limit The method detection limit is measured with a matrix solution (ICS). The ICS solutions contain matrix and a low concentration (5 µg/l) of the analyte itself. See for matrix concentrations table 1. Each solution is measured 10 times. The standard deviation multiplied by 3 is the detection limit in the unit mg/l. The method detection limit expressed in mass concentration depends on the amount of the soil that s digested and the end volume. Therefore the method detection limit expressed in mass content is calculated with 2.5 gram to 100 ml. The results are summarized in table 7. Discussion: For the most elements the method detection limit are between 0.1 and 3 mg/kg. Table 7: Method detection limit: MDL in matrix Element wavelength mg/l matrix solution mg/kg dw (2.5g/100 ml) Ag 328,1 atom axial 0,003 0,10 - Ag 338,3 atom axial 0,002 0,09 As 189,0 atom axial 0,034 1,72 As 193,7 atom axial 0,072 2,88 4 As 197,2 atom axial 0,066 2,64 Reference (NL) (informative)

17 Page 17 van 36 pages Ba 234,5 ion rad 0,012 0,46 15 Ba 455,4 ion rad 0,008 0,31 Ba 493,4 ion rad 0,007 0,36 Be 234,9 atom axial 0,003 0,12 Be 313,0 ion axial 0,003 0,10 0,1 Be 313,1 ion axial 0,002 0,11 Cd 214,4 atom axial 0,003 0,12 0,17 Cd 226,5 ion axial 0,004 0,17 Cd 228,8 atom axial 0,003 0,16 Co 228,6 ion axial 0,003 0,12 1 Co 230,8 ion axial 0,003 0,12 Co 238,9 ion axial 0,025 1,27 Cr 205,6 ion axial 0,031 1,22 15 Cr 206,2 ion axial 0,036 1,42 Cr 267,7 ion axial 0,031 1,53 Cu 224,7 ion axial 0,014 0,72 Cu 324,7 atom axial 0,015 0,62 5 Cu 327,4 atom axial 0,018 0,71 Mo 202,0 ion axial 0,005 0,19 1,5 Mo 203,8 ion axial 0,022 1,10 Mo 204,6 ion axial 0,015 0,59 Ni 221,6 ion axial 0,008 0,31 Ni 231,6 ion axial 0,008 0,31 3 Ni 233,0 atom axial 0,019 0,94 Pb 217,0 atom axial 0,074 2,97 Pb 220,3 ion axial 0,019 0,77 13 Pb 283,3 atom axial 0,085 4,25 Sb 206,8 atom axial 0,037 1,49 Sb 217,6 atom axial 0,028 1,12 Se 196,0 atom axial 0,080 3,19 Sn 189,9 ion axial 0,021 0,83 6 Sn 242,2 atom axial 0,065 3,24 Tl 190,8 ion axial 0,033 1,31 0,3 Tl 351,9 atom axial 0,014 0,69 V 290,9 ion rad 0,010 0,41 4 V 292,4 ion rad 0,009 0,35 V 310,2 ion rad 0,003 0,16 Zn 202,5 ion rad 0,022 0,89 17 Zn 206,2 ion rad 0,065 3,27 Zn 213,8 atom rad 0,029 1, Precision The reference materials used for investigation of the precision (expressed as within lab reproducibility) are the same as used in 4.1. The selected materials were measured on eight different days. The reference materials, digested with aqua regia, were used. The results are reported in table 8. The red marked values are greater than 10%. See annex 6.5 for an overview of the concentration levels of the measured samples. Discussion: The precision is for most elements better than 10%, except for those elements where the concentration is at a low (<5 times DL) level. This corresponds in nearly all cases with the (red) marked values in table 8. The average overall precision is 6.8%.

18 Page 18 van 36 pages 4.7 Recovery (spike and dilution). The recovery is investigated with both methods given in the proposed standard: A addition of a multi element standard to a matrix solution (ICS) and Measurements in the original sample and a 2-3 times diluted samples. A multi element standard solution was added to ICS with a solution concentration of 0,5 and 5 mg/l. This was also done to a reagent blank. The recovery of the spike to the ICS solution was calculated against the addition to the reagent blank and the theoretical concentration. The recovery after dilution was determined by manual dilution of the digest before measurement. The standard proposes a dilution by 5 times but because of the low concentration of the elements of interest in the digests, a 2-3 time dilution was used here. The results of the addition are reported in table 9. The results from the dilution experiment in annex [6.3]. The overall recovery ratio after 2-fold dilution is 1,03 +/- 0.05(5,1%) and for 3-fold dilution /- 0.06(6,1%) which is well within the required 20%. Discussion: Nearly all recoveries of the spike are within the limits of % except for Ni at low level (respectively 79,1 and 74,8%) and Zn. For Zn there is not a clear explanation for the slight deviation of the 80 % criteria but might be cause by a contamination of the blank addition because the recovery is low for all lines at all view directions. Although the dilution factor is 2-3 fold all the recovery values are within the limits for those elements that have a remaining concentration after dilution above 5 times DL. The recovery criterion (after digestion) is only applicable for those samples that contain high concentrations of the elements of interest. For lower concentrations and subsequent measurement close to the DL, dilution of the sample is not recommended.

19 Page 19 van 36 pages Table 8: Precision (in %): CRM Fenelab LKSD- STSD- CRM CRM CRM AMB AMB AMB Average 145R R 141R sludge soil biowaste Ag atom Axial 10,5% 14,4% 12,5% Al atom rad 5,0% 5,4% 6,9% 4,2% 6,0% 6,6% 7,2% 7,0% 6,9% 5,9% 6,1% As atom axial 17,8% 9,9% 7,4% 10,2% 18,1% 19,0% 13,7% Ba ion rad 18,5% 6,7% 6,5% 5,1% 5,4% 5,7% 6,4% 31,8% 6,9% 6,9% 10,0% Be ion axial 9,3% 4,9% 14,1% 3,3% 5,4% 14,3% 3,6% 5,1% 7,5% Ca ion rad 5,4% 4,9% 4,5% 3,6% 4,8% 6,6% 4,6% 6,7% 5,3% 4,1% 5,0% Cd atom axial 7,5% 6,5% 17,2% 11,7% 3,6% 9,3% Co ion axial 6,5% 5,4% 7,5% 8,5% 9,1% 4,9% 8,0% 8,1% 11,6% 7,7% Co ion axial IEC 7,2% 5,5% 9,4% 10,6% 11,8% 5,0% 8,7% 8,7% 8,4% Cr ion axial 3,9% 3,2% 8,1% 5,4% 5,1% 4,2% 3,9% 5,8% 5,2% 5,0% Cu atom axial 4,7% 8,2% 4,0% 4,6% 3,8% 5,5% 4,3% 5,9% 8,1% 5,4% Fe ion rad 3,8% 1,6% 3,4% 3,0% 2,3% 4,0% 3,6% 2,6% 3,3% 1,6% 2,9% Mg atom rad 5,2% 3,7% 5,9% 4,4% 5,4% 5,1% 5,7% 7,1% 6,7% 5,9% 5,5% Mn ion rad 4,7% 5,5% 6,1% 7,7% 8,1% 7,4% 3,3% 14,7% 14,8% 15,4% 8,8% Mo ion axial 8,1% 5,4% 5,0% 15,8% 8,6% Ni ion axial 3,8% 4,8% 6,3% 4,0% 5,0% 4,1% 5,4% 7,9% 5,2% Ni ion axial IEC 3,9% 6,1% 5,8% 6,7% 4,2% 5,9% 10,4% 6,1% P atom axial 2,9% 3,0% 3,3% 4,0% 3,8% 2,8% 3,1% 5,3% 4,3% 3,6% Pb ion axial 3,8% 4,7% 4,5% 3,5% 4,8% 6,2% 4,3% 5,8% 7,0% 4,9% S atom axial 1,7% 4,4% 1,8% 5,3% 3,3% 1,6% 22,7% 4,1% 3,4% 5,4% Sb atom axial 12,6% 12,6% Se atom axial Sn ion axial 5,2% 3,3% 6,6% 5,0% Ti ion rad 5,2% 3,4% 4,8% 3,3% 4,6% 5,0% 3,6% 3,8% 5,5% 5,6% 4,5% Tl ion axial V ion rad 7,1% 6,1% 3,9% 2,8% 3,5% 5,2% 3,0% 4,3% 8,6% 4,9% Zn ion rad 5,4% 2,7% 3,8% 2,8% 4,0% 5,0% 4,9% 5,5% 5,4% 4,4% Zn ion rad IEC 5,4% 2,7% 3,8% 2,8% 4,0% 5,0% 4,9% 5,5% 5,4% 4,4% Overall 6,8%

20 Page 20 van 36 pages Table 9: Spike recovery (in %): Ag As Ba Be Cd Cd Co Cr Cu Mo Ni Ni Pb Sb Se Sn Tl Tl V atom atom ion ion atom atom ion ion atom ion ion ion ion atom atom ion ion ion ion axial axial rad axial axial radial axial axial axial axial axial radial axial axial axial axial axial radial rad spike level (mg/l) recovery corrected *(%) spike level (mg/l) recovery corrected *(%) Ag As Ba Be Cd Co Cr Cu Mo Ni Pb Sb V atom atom ion Atom ion ion ion atom ion ion atom atom ion axial axial rad axial axial axial axial axial axial axial axial axial rad spike level (mg/l) recovery corrected *(%) spike level (mg/l) recovery corrected *(%)