SIST EN 15510:2007
(Main)Animal feeding stuffs - Determination of calcium, sodium, phosphorus, magnesium, potassium, iron, zinc, copper, manganese, cobalt, molybdenum, arsenic, lead and cadmium by ICP-AES
Animal feeding stuffs - Determination of calcium, sodium, phosphorus, magnesium, potassium, iron, zinc, copper, manganese, cobalt, molybdenum, arsenic, lead and cadmium by ICP-AES
This European Standard specifies inductively coupled plasma atomic emission spectroscopy (ICP-AES) method for the determination of:
- minerals calcium, sodium, phosphorus, magnesium and potassium and the elements iron, zinc, copper, manganese, cobalt, molybdenum in animal feeding stuffs,
- elements arsenic, lead and cadmium in minerals on their own, in pre-mixtures or mixtures for use in animal nutrition.
The method detection limit for each element is dependent on the sample matrix as well as of the instrument. The method is not applicable for determination of low concentrations of elements. The limit of quantification should be 3 mg/kg or lower.
NOTE This method can also be used for the determination of minerals in products with high mineral content (> 5%), yet for this purpose, other more precise analytical techniques are available.
Futtermittel - Bestimmung von Calcium, Natrium, Phosphor, Magnesium, Kalium, Eisen, Zink, Kupfer, Mangan, Cobalt, Molybdän, Arsen, Blei und Cadmium mittels ICP-AES
Diese Europäische Norm legt ein Verfahren mittels Atomemissionsspektrometrie mit induktiv gekoppeltem Plasma (ICP AES) zur Bestimmung von
den Mineralstoffen Calcium, Natrium, Phosphor, Magnesium und Kalium und den Elementen Eisen, Zink, Kupfer, Mangan, Cobalt und Molybdän in Futtermitteln,
den Elementen Arsen, Blei und Cadmium in Mineralien für sich allein, in Vormischungen und Mischungen für die Anwendung in Tiernahrung
fest.
Die Nachweisgrenze des Verfahrens hängt bei jedem Element sowohl von der Probenmatrix als auch von dem Gerät ab. Das Verfahren ist nicht für die Bestimmung von geringen Elementkonzentrationen anwendbar. Die Bestimmungsgrenze sollte bei 3 mg/kg oder niedriger liegen.
ANMERKUNG Dieses Verfahren kann für die Bestimmung von Mineralstoffen in Produkten mit einem hohen Mineral¬stoffgehalt (> 5 %) eingesetzt werden, für diesen Zweck stehen aber auch andere genauere Analysenverfahren zur Verfügung.
Aliments des animaux - Détermination des teneurs en calcium, sodium, phosphore, magnésium, potassium, fer, zinc, cuivre, manganese, cobalt, molybdene, arsenic, plomb et cadmium par ICP-AES
La présente Norme européenne spécifie une méthode de spectrométrie d'émission atomique a plasma a couplage inductif (ICP-AES) pour la détermination de la teneur en :
minéraux (calcium, sodium, phosphore, magnésium et potassium) et en éléments (fer, zinc, cuivre, manganese, cobalt, molybdene) dans les aliments pour animaux ;
éléments (arsenic, plomb et cadmium) dans des minéraux purs, dans des pré-mélanges ou des mélanges utilisés pour nourrir des animaux.
La limite de détection de la méthode pour chacun des éléments est fonction de la matrice de l'échantillon et de l'instrument. Cette méthode ne permet pas la détermination des éléments en faibles concentrations. Il convient que la limite de quantification soit de 3 mg/kg ou moins.
NOTE La présente méthode peut etre utilisée pour la détermination de la teneur en minéraux dans les produits a forte concentration minérale ( 5 %). D'autres techniques d’analyse plus précises sont néanmoins applicables pour ce genre de détermination.
Krma - Določevanje kalcija, natrija, fosforja, magnezija, kalija, železa, cinka, bakra, mangana, kobalta, molibdena, arzena, svinca in kadmija z ICP-AES
General Information
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Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Animal feeding stuffs - Determination of calcium, sodium, phosphorus, magnesium, potassium, iron, zinc, copper, manganese, cobalt, molybdenum, arsenic, lead and cadmium by ICP-AESAliments des animaux - Détermination des teneurs en calcium, sodium, phosphore, magnésium, potassium, fer, zinc, cuivre, manganese, cobalt, molybdene, arsenic, plomb et cadmium par ICP-AESFuttermittel - Bestimmung von Calcium, Natrium, Phosphor, Magnesium, Kalium, Eisen, Zink, Kupfer, Mangan, Cobalt, Molybdän, Arsen, Blei und Cadmium mittels ICP-AESTa slovenski standard je istoveten z:EN 15510:2007SIST EN 15510:2007en,fr,de65.120KrmilaAnimal feeding stuffsICS:SLOVENSKI
STANDARDSIST EN 15510:200701-november-2007
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15510August 2007ICS 65.120 English VersionAnimal feeding stuffs - Determination of calcium, sodium,phosphorus, magnesium, potassium, iron, zinc, copper,manganese, cobalt, molybdenum, arsenic, lead and cadmium byICP-AESAliments des animaux - Détermination des teneurs encalcium, sodium, phosphore, magnésium, potassium, fer,zinc, cuivre, manganèse, cobalt, molybdène, arsenic,plomb et cadmium par ICP-AESFuttermittel - Bestimmung von Calcium, Natrium,Phosphor, Magnesium, Kalium, Eisen, Zink, Kupfer,Mangan, Cobalt, Molybdän, Arsen, Blei und Cadmiummittels ICP-AESThis European Standard was approved by CEN on 30 June 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the CEN 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15510:2007: E
EN 15510:2007 (E) 2 Contents Page Foreword.3 1 Scope.4 2 Normative references.4 3 Terms and definitions.4 4 Principle.5 5 Reagents.5 6 Apparatus, usual laboratory apparatus and, in particular, the following.7 7 Sampling.7 8 Preparation of the test sample.8 9 Procedure.9 10 Calculation and expression of the result.13 11 Precision.15 12 Test report.20 Annex A (informative)
Results of the interlaboratory test.21 Annex B (informative)
Notes on the detection technique, interferences and quantification.26 Bibliography.29
EN 15510:2007 (E) 3 Foreword This document (EN 15510:2007) has been prepared by Technical Committee CEN/TC 327 “Animal feeding stuffs – Methods of sampling and analysis”, 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 February 2008, and conflicting national standards shall be withdrawn at the latest by February 2008. 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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EN 15510:2007 (E) 4 1 Scope This European Standard specifies inductively coupled plasma atomic emission spectroscopy (ICP-AES) method for the determination of: minerals calcium, sodium, phosphorus, magnesium and potassium and the elements iron, zinc, copper, manganese, cobalt, molybdenum in animal feeding stuffs, elements arsenic, lead and cadmium in minerals on their own, in pre-mixtures or mixtures for use in animal nutrition. The method detection limit for each element is dependent on the sample matrix as well as of the instrument. The method is not applicable for determination of low concentrations of elements. The limit of quantification should be 3 mg/kg or lower. NOTE This method can also be used for the determination of minerals in products with high mineral content (> 5%), yet for this purpose, other more precise analytical techniques are available. 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. EN ISO 3696, Water for analytical laboratory use – Specification and test methods (ISO 3696:1987) ISO 6498, Animal feeding stuffs – Preparation of test samples 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 limit of detection (LOD) smallest measured content from which it is possible to deduce the presence of the analyte with reasonable statistical certainty NOTE The limit of detection is numerically equal to three times the standard deviation of the mean of blank determinations (n ≥ 10, were n = number of measures) performed under reproducibility conditions. 3.2 limit of quantification (LOQ) lowest content of the analyte that can be measured with reasonable statistical certainty NOTE If both trueness and precision are constant over a concentration range around the limit of detection, then the limit of quantification is numerically equal to ten times the standard deviation of the mean of blank determinations (n ≥ 10, were n = number of measures) performed under reproducibility conditions. 3.3 feed additives substances are feed additives when they comply with the definition of feed additives given in regulation EU 1831/2003' 3.4 animal feeding stuffs substances that comply with the definition of animal feeding stuffs given in regulation EU 178/2002'
EN 15510:2007 (E) 5 4 Principle For the determination of the minerals calcium, sodium, phosphorus, magnesium and potassium and the elements iron, zinc, copper, manganese, cobalt, molybdenum, a test portion of the sample is ashed and dissolved in hydrochloric acid (in the case of organic feeding stuffs) or wet digested with hydrochloric acid (in the case of mineral compounds). For the determination of the elements arsenic, cadmium and lead, a test portion of the sample is wet digested with nitric acid. The concentration of the elements calcium, sodium, phosphorus, magnesium, potassium, iron, zinc, copper, manganese, cobalt, molybdenum, arsenic, cadmium and lead is determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) using external calibration or standard addition technique.
WARNING – Use of this European Standard can involve hazardous materials, operations and equipment. This standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this European Standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 5 Reagents Use only reagents of recognized analytical grade, unless otherwise specified. 5.1 Water, complying with grade 2 as defined in EN ISO 3696. 5.2 Nitric acid, concentrated, not less than 65 % (mass fraction), having a density of approximately (HNO3) 1,42 g/ml. 5.3 Dilute nitric acid, to be prepared by mixing 1 volume of nitric acid (5.2) with 1 volume of water. 5.4 Nitric acid solution of 5 % (m/v), to be prepared: pipette 160 ml of dilute nitric acid (5.3) into a
1 000 ml volumetric flask (6.7) and fill to the mark with water. 5.5 Nitric acid solution of 2 % (v/v), to be prepared: pipette 20 ml of nitric acid (5.2) into a 1 000 ml volumetric flask (6.7) and fill to the mark with water. 5.6 Hydrochloric acid, concentrated, not less than 30 % (mass fraction), having a density of approximately (HCl) 1,15 g/ml. 5.7 Dilute hydrochloric acid, to be prepared by mixing 1 volume of hydrochloric acid (5.6) with 1 volume of water. 5.8 Hydrochloric acid solution of 1 % (m/v), to be prepared: pipette 60 ml of dilute hydrochloric acid (5.7) into a 1 000 ml volumetric flask (6.7) and fill to the mark with water. 5.9 Element stock solutions Ca, Na, P, Mg, K, Fe, Zn, Cu, Mn, Co, Mo, Cd, Pb, As c = 1 000 mg/l. The user should choose a suitable stock solution. Both single-element stock solutions and multi-element stock solutions with adequate specification stating the acid used and the preparation technique are commercially available. It is advisable to use certified stock solutions.
EN 15510:2007 (E) 6 Stock solutions are not to be used after the expiry date. NOTE Element stock solutions with concentrations different from 1 000 mg/l may also be used. 5.10 Standard solutions 5.10.1 General Depending on the scope, different multi-element standard solutions may be necessary. In general, when combining multi-element standard solutions, their chemical compatibility and the possible hydrolysis of the components shall be regarded. Spectral interferences from other elements in multi-element standard solutions also need to be considered (Annex B.2.2). The examples given below also consider the measuring range of various inductively coupled plasma atomic emission spectrometers and the expected concentration of the element in animal feeding stuffs. The multi-element standard solutions are considered to be stable for several months, if stored in the dark.
Other combinations of elements at different concentrations can be used, provided that the element stock solutions (5.9) are diluted with the same acid and equal concentration as the acid in the test solution to a range of standards that covers the concentrations of the elements to be determined. 5.10.2 Multi-element standard solution – Minerals in 1 % HCl c (Ca, Na, P, Mg, K) = 40 mg/l
Pipette 40,0 ml of each element stock solution (Ca, Na, P, Mg, K) (5.9) into a 1 000 ml volumetric flask (6.7). Add 60 ml of dilute hydrochloric acid (5.7). Fill to the mark with water and transfer to a suitable storage bottle. 5.10.3 Multi-element standard solution - Fe, Zn, Cu, Mn, Co, Mo in 1 % HCl c (Fe, Zn, Cu, Mn, Co, Mo) = 50 mg/l Pipette 50,0 ml of each element stock solution (Fe, Zn, Cu, Mn, Co, Mo) (5.9) into a 1 000 ml volumetric flask (6.7). Add 60 ml of dilute hydrochloric acid (5.7). Fill to the mark with water and transfer to a suitable storage bottle. 5.10.4 Multi-element standard solution – Cd, Pb, As in 5 % HNO3 c (Cd, Pb, As) = 100 mg/l
Pipette 100,0 ml of each element stock solution (Cd, Pb, As) (5.9) into a 1000 ml volumetric flask (6.7). Add 160 ml dilute nitric acid (5.3). Fill to the mark with water and transfer to a suitable storage bottle.
EN 15510:2007 (E) 7
6 Apparatus, usual laboratory apparatus and, in particular, the following. 6.1 Laboratory grinder 6.1.1 Use laboratory grinders that are equipped such that they do not lead to contamination of the samples. 6.1.2 Laboratory grinder capable of grinding to a particle size of less than or equal to 1 mm, e.g. a knife mill or equivalent. 6.1.3 Laboratory grinder capable of grinding to a particle size of less than or equal to 0,1 mm, e.g. a ball mill or equivalent. 6.1.4 Mortar with pestle, free of contamination. 6.2 Analytical balance, capable of weighing to an accuracy of 1 mg. 6.3 Electric hot plate, with temperature control. 6.4 Ashing crucibles, of platinum, quartz or porcelain. 6.5 Electric muffle-furnace, capable of being maintained at a temperature of 450 °C ± 20 °C. The real temperature in the furnace has to be checked, because this temperature may be substantially different from the adjust temperature. 6.6 Beaker, of capacities 100 ml, 250 ml.
6.7 One-mark volumetric flasks, of capacities 100 ml, 500 ml, 1 000 ml. 6.8 Inductively coupled plasma – Atomic Emission Spectrometer
The instrument shall be equipped with a radial plasma as a minimum requirement; an axial plasma is equally acceptable. Background correction shall also be performed when necessary. Settings of the working conditions (e.g. viewing height, gas flows, RF or plasma power, sample uptake rate, integration time, number of replicates, …) shall be optimised according the manufacturer’s instructions. 6.9 Freeze drying equipment, capable of freeze-drying liquid animal feeding stuffs. 7 Sampling Sampling is not part of the method specified in this Standard. A recommended sampling method is given in EN ISO 6497. It is important that the laboratory receives a sample that is truly representative and has not been damaged or changed during transport or storage.
EN 15510:2007 (E) 8 8 Preparation of the test sample 8.1 General Prepare the test sample in accordance with ISO 6498.
Grinding must be carried out in conditions such that the substance is not appreciably heated.
Operation is to be repeated as many times as is necessary and it must be affected as quickly as possible in order to prevent any gain or loss of constituents (water).
Whole ground product is placed in a flask made of e.g. polypropylene, which can be stoppered and stored in such way to prevent any change in composition.
Before any weighing is carried out for the analysis, the whole test sample must be thoroughly mixed for reasons of homogeneity.
8.2 Animal feeding stuffs which can be ground as such
Grind the laboratory sample (usually 500 g), using a grinder (6.1.2) or mortar (6.1.4), until a particle size of
1 mm or less has been reached.
8.3 Liquid animal feeding stuffs
8.3.1 General Liquid feeding stuffs shall be pre-dried according to the procedure described in 8.3.2 or freeze-dried according to the procedure described in 8.3.3. 8.3.2 Pre-drying Pre-dry the laboratory sample at 70 °C ± 5 °C over at least 16 h to reduce the moisture content. The mass of the sample before and after the pre-drying is determined using an analytical balance (6.2). Grind the pre-dried sample in accordance with 8.2.
8.3.3 Freeze-drying Freeze-dry the laboratory sample following the instructions of the freeze-drying equipment (6.9). The mass of the sample before and after the freeze-drying is determined using an analytical balance (6.2). Grind the freeze-dried sample in accordance with 8.2.
8.4 Mineral animal feeding stuffs Mineral compounds, except mineral products containing crystalline water, e.g. MgCl2 6H2O, shall be ground using a grinder (6.1.3) or mortar until a particle size of 0,1 mm or less has been reached. Mineral products containing crystalline water should not be ground.
EN 15510:2007 (E) 9 9 Procedure 9.1 Digestion 9.1.1 Selection of the procedure 9.1.1.1 Determination of Ca, Na, P, Mg, K, Fe, Zn, Cu, Mn, Co, Mo
If the test sample concerns a mineral compound or a product potentially containing phosphates, proceed in accordance with 9.1.2.
If the test sample contains organic substances and if it is free from phosphates rendering insoluble products on ashing, proceed in accordance with 9.1.3.
If the test sample contains organic substances and phosphates, proceed in accordance with 9.1.2. 9.1.1.2 Determination of Cd, Pb, As in minerals
For the determination of Cd, Pb and As in minerals, proceed in accordance with 9.1.4.
9.1.2 Extraction with 1% HCl
Weigh about 1 g of the prepared test sample to the nearest 1 mg into a beaker of 250 ml (6.6).
Add 30 ml dilute hydrochloric acid (5.7). Add about 100 ml of water. Cover the beaker (6.6) with a watch-glass and boil for 30 min on a hot plate (6.3). Allow to cool. Transfer the liquid into a 500 ml volumetric flask (6.7), rinsing the beaker and the watch-glass several times with water.
Leave to cool, dilute to the mark with water. After homogenising, filter through a dry folded filter paper into a dry conical flask. Use the first portion of the filtrate to rinse the glass ware and discard that part. If the determination is not carried out immediately, the conical flask with the filtrate shall be stoppered. Carry out a blank determination at the same time as the extraction, with only the reagents and follow the same procedure as for the samples. Proceed in accordance with 9.2. When the expected concentration of the element is lower than 100 mg/kg, proceed as described in 9.1.2, but use 12 ml dilute hydrochloric acid (5.7) and 70 ml of water, and transfer the liquid into a 100 ml volumetric flask (6.7). 9.1.3 Dry ashing – 1% HCl
Weigh 5 g of the prepared test sample to the nearest 1 mg in an ashing crucible (6.4).
Ash in the furnace (6.5), set at a temperature of 450 °C, until white or grey ash is obtained (a small quantity of carbon does not interfere). Transfer the ash to a 250 ml beaker (6.6) with 30 ml of dilute hydrochloric acid (5.7). Add 100 ml of water. Cover the beaker (6.6) with a watch-glass and boil for 30 min on a hot plate (6.3).
Allow to cool. Transfer the liquid into a 500 ml volumetric flask (6.7), rinsing the beaker and the watch-glass several times with water.
Leave to cool, dilute to the mark with water.
EN 15510:2007 (E) 10 After homogenising, filter through a dry folded filter paper into a dry conical flask. Use the first portion of the filtrate to rinse the glassware and discard that part. If the determination is not carried out immediately, the conical flask with the filtrate shall be stoppered. Carry out a blank determination at the same time as the extraction, with only the reagents and follow the same procedure as for the samples. Proceed in accordance with 9.2. When the expected concentration of the element is lower than 100 mg/kg, proceed as described in 9.1.3, but use 12 ml dilute hydrochloric acid (5.7) and about 70 ml of water, and transfer the liquid into a 100 ml volumetric flask (6.7). 9.1.4 Extraction with 5% HNO3
Weigh about 2 g of the prepared test sample to the nearest 1 mg into a beaker of 100 ml (6.6).
Add 16 ml dilute nitric acid (5.3). Add about 70 ml of water. Cover the beaker (6.6) with a watch-glass and boil for 30 min on a hot plate (6.3). Allow to cool. Transfer the liquid into a 100 ml volumetric flask (6.7), rinsing the beaker and the watch-glass several times with water.
Leave to cool, dilute to the mark with water.
After homogenising, filter through a dry folded filter paper into a dry conical flask. Use the first portion of the filtrate to rinse the glassware and discard that part. If the determination is not carried out immediately, the conical flask with the filtrate shall be stoppered. Carry out a blank determination at the same time as the extraction with only the reagents and follow the same procedure as for the samples. Proceed in accordance with 9.2. 9.2 Calibration 9.2.1 General Calibration shall be performed by means of external calibration or standard addition technique. It is important that the measurements are made in the linear range of the instrument. Appropriate matrix matching of the calibration solutions shall be performed if an (external) calibration method is used (see Annex B). 9.2.2 External calibration The calibration is performed with at least two calibration solutions of which one is a blank calibration solution. In all cases linearity should be checked on regular basis. If linearity is guaranteed, calibrate with at least two calibration solutions, if linearity is not guaranteed, calibrate with at least three equidistant calibration solutions (B.3.2). 9.2.3 Standard addition technique The standard addition curve should consist of at least two points one of which is an addition (B.3.4). For those elements whose concentration is near the limit of quantification, the standard addition curve should consist of at least four points of which three are additions. If three additions are used, the concentration of the highest standard should be three to five times the concentration in the sample solution.
9.2.4 Example of calibration with one addition after dry ashing – 1% HCl
EXAMPLE
Determination of copper in a mixed feed with expected concentration 200 mg/kg Cu.
EN 15510:2007 (E) 11 9.2.4.1 Preparation of the test solution Pipette 50,0 ml of the filtrate of the test portion (9.1.3) into a 100 ml volumetric flask (6.7) and fill to the mark with 1 % hydrochloric acid solution (5.8). 9.2.4.2 Preparation of the blank solution Pipette 50,0 ml of the filtrate of the blank (9.1.3) into a 100 ml volumetric flask (6.7) and fill to the mark with 1 % hydrochloric acid solution (5.8). 9.2.4.3 Preparation of the addition Pipette 50,0 ml of the filtrate of the test portion (9.1.3) into a 100 ml volumetric flask (6.7), add 2,0 ml of the multi-element standard solution – Fe, Zn, Cu, Mn, Co, Mo in 1 % HCl (5.10.3) and fill to the mark with 1 % hydrochloric acid solution (5.8). 9.2.5 Example of calibration with one addition after wet digestion – 1 % HCl EXAMPLE
Determination of calcium in a mineral compound with expected concentration 2 000 mg/kg Ca. 9.2.5.1 Preparation of the test solution Pipette 50,0 ml of the filtrate of the test portion (9.1.2) into a 100 ml volumetric flask (6.7) and fill to the mark with 1 % hydrochloric acid solution (5.8). 9.2.5.2 Preparation of the blank solution Pipette 50,0 ml of the filtrate of the blank (9.1.2) into a 100 ml volumetric flask (6.7) and fill to the mark with 1 % hydrochloric acid solution (5.8). 9.2.5.3 Preparation of the addition Pipette 50,0 ml of the filtrate of the test portion (9.1.2) into a 100 ml volumetric flask (6.7), add 10 ml of the multi-element standard solution – Minerals in 1 % HCl (5.10.2) and fill to the mark with 1 % hydrochloric acid solution (5.8). 9.2.6 Example of calibration with one addition after wet digestion – 5 % HNO3 EXAMPLE
Determination of arsenic in a mineral compound with expected concentration 20 mg/kg As. 9.2.6.1 Preparation of the test solution Pipette 10,0 ml of the filtrate of the test portion (9.1.4) into a test tube for ICP. 9.2.6.2 Preparation of the blank solution Pipette 10,0 ml of the filtrate of the blank (9.1.4) into a test tube for ICP.
9.2.6.3 Preparation of the addition Pipette 10,0 ml of the filtrate of the test portion (9.1.4) into a test tube for ICP. Pipette 40 µl of the multi-element standard solution – Cd, Pb, As in 5 % HNO3 (5.10.4).
EN 15510:2007 (E) 12 9.3 Determination 9.3.1 General Analytical lines, selectivity, limits of determination and quantification, precision, linear working area, and interferences have to be established before operating the ICP-AES system. 9.3.2 Determination by inductively coupled plasma – atomic emission spectrometry 9.3.2.1 General Table 1 gives relevant analytical lines and possible interferences for the determination with ICP-AES. Wavelengths other than those specified in Table 1 can also be used (see also Annex B). Table 1 — Selected emission wavelengths and interferences for determination with ICP-AES Element Wavelength of emission (nm) Interference Element Wavelength of emission (nm) Interference 188,979
257,610 Fe, Mo, Cr 189,042
Mn 293,306 Al, Fe 193,696
202,030 Al, Fe As 197,197
Mo 204,598
315,887 Co
330,237
317,933 Fe, V
588,995
Ca 393,366
Na 589,592 Ar 214,438
178,287 I 226,502
213,618 Cu, Fe, Mo, Zn Cd 228,802
214,914 Cu, Al, Mg Co 228,616 Ti
P
177,428 Cu 324,754 Ti, Fe
216,999
Cu 327,396
220,353 Al, Co, Ti 238,200 Co
Pb
261,418
Fe 259,940
206,200 Cr 766,490 Mg, Ar
213,856 P, Cu, Ni, Fe K 769,900
Zn
279,079
279,553
Mg 285,213 Fe
9.3.2.2 External calibration method Aspirate the blank test solution (9.1), the calibration solutions (9.2.1), and the test solution (9.1) in ascending order separately into the plasma and measure the emission of the element to be determined. Each value should be determined from at least three individual measurements. Average the values if the values fall within an accepted range. After each measurement, aspirate 2 % nitric acid solution (5.5). 9.3.2.3 Standard addition technique Aspirate the blank test solution (9.2.4.2 or 9.2.5.2 or 9.2.6.2), the test solution (9.2.4.1 or 9.2.5.1 or 9.2.6.1), and the addition (9.2.4.3 or 9.2.5.3 or 9.2.6.3) in ascending order separately into the plasma, and measure the emission of the element to be determined. Perform at least two replicates. Average the values if the values fall within an accepted range. After each measurement, aspirate 2 % nitric acid solution (5.5).
EN 15510:2007 (E) 13 10 Calculation and expression of the result NOTE Net signal is defined as the number of counts at the selected wavelength, corrected for background contributions. 10.1 External calibration In the case of a linear calibration curve constructed with one blank calibration solution and one calibration solution, the calibration function can be described as follows: abcS+×=stst (1)
where stS
is the net signal of the calibration solution; stc
is the concentration, in mg/l, of the calibration solution; b
is the slope; a
is the intersection. Calculate the element concentration fc, in mg/l, in the filtrate of the test portion using the slope b and the intersection a found in (1) as follows: baScff−= (2) where fS
is the net signal of the test solution. 10.2 Standard addition method with only one addition In the simplest case of standard addition, where only one addition is made, the element concentration cf, in mg/l, in the filtrate of the test portion is determined as follows: ()fssfVSScVSc×−××=010 (3) where sc
is the concentration, in mg/l, of the standard solution; sV
is the volume, in l, of the standard solution added; fV
is the volume, in l, of the filtrate of the test portion used to prepare the test solution; 0S
is the net signal of the test solution; 1S
is the net signal after addition. 10.3 Standard addition method with several additions In case of several additions, regression techniques on the linear model of variable y as a function of variable x, have to be used to determine the element concentration of the test solution. Generally this model can be written as:
EN 15510:2007 (E) 14 iixbay×+= (4) In this particular case of three standard additions,
iiSy=
(for i = 0, 1, 2, 3) (5) isiVcx×=
(for i = 0, 1, 2, 3) (6) where sc
is the concentration, in mg/l, of the standard solution; iV
are the various volumes, in l, of the standard solution added; iS
are the net signals after the various additions. The values of a and b can then be calculated as follows: ()∑∑−×∑∑−∑×=22iiiiiixxnyxyxnb (7) nxbyaii∑∑×−= (8) where
n is the number of solutions measured (n= 4 in case of three additions). The element concentration cf, in mg/l, of the filtrate of the test portion can then be found using the following equation: ffVbac= (9) where
fV
is the volume, in litres, of the filtrate of the test portion used to prepare the test solution. 10.4 Calculation of the element content in the sample The element content in the sample or mass fraction of element welem, expressed in mg of element per kg of animal feeding stuff, is determined using the following equation: ()tblfelemVmccw×−= (10) where fc is the concentration, in mg/l, of the filtrate of the test portion, as determined using equation (2) or (3) or (9); blc
is the concentration, in mg/l, of the blank solution; m
is the mass of sample, in kg, taken for the extraction, and corrected for water content; tV
is the total volume, in l, of extract (filtrate of the test portion).
EN 15510:2007 (E) 15 If the sample has been diluted, take into account the dilution factor. If the sample has been pre-dried or freeze-dried
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