SIST EN 16278:2012

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.RFuttermittel - Bestimmung von anorganischem Arsen mit Atomabsorptionsspektrometrie-Hydridtechnik (HD-AAS) nach Mikrowellen-Extraktion und Trennung durch Festphasenextraktion (SPE)Aliments des animaux - Dosage de l'arsenic inorganique par spectrométrie d'absorption atomique par génération d'hydrures après extraction par micro-ondesAnimal feeding stuffs - Determination of inorganic arsenic by hydride generation atomic absorption spectrometry (HG-AAS) after microwave extraction and separation by solid phase extraction (SPE)65.120KrmilaAnimal feeding stuffsICS:Ta slovenski standard je istoveten z:EN 16278:2012SIST EN 16278:2012en,fr,de01-september-2012SIST EN 16278:2012SLOVENSKI
STANDARD



SIST EN 16278:2012



EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16278
July 2012 ICS 65.120 English Version
Animal feeding stuffs - Determination of inorganic arsenic by hydride generation atomic absorption spectrometry (HG-AAS) after microwave extraction and separation by solid phase extraction (SPE)
Aliments des animaux - Dosage de l'arsenic inorganique par spectrométrie d'absorption atomique par génération d'hydrures après extraction par micro-ondes
Futtermittel - Bestimmung von anorganischem Arsen mit Atomabsorptionsspektrometrie-Hydridtechnik (HD-AAS) nach Mikrowellen-Extraktion und Trennung durch Festphasenextraktion (SPE) This European Standard was approved by CEN on 17 May 2012.
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
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16278:2012: ESIST EN 16278:2012



EN 16278:2012 (E) 2 Contents Page Foreword .31Scope .42Normative references .43Principle .44Reagents .45Apparatus and equipment .66Procedure .77Calculation . 108Precision . 109Test report . 11Annex A (informative)
Results of the interlaboratory tests. 12Annex B (informative)
Flowchart Animal feeding stuffs — Determination of inorganic arsenic by hydride generation atomic absorption spectrometry (HG-AAS) after microwave extraction and separation by solid phase extraction (SPE) . 13Bibliography . 18 SIST EN 16278:2012



EN 16278:2012 (E) 3 Foreword This document (EN 16278:2012) has been prepared by Technical Committee CEN/TC 327 “Animal feeding stuffs”, 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 January 2013, and conflicting national standards shall be withdrawn at the latest by January 2013. 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. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. 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 16278:2012



EN 16278:2012 (E) 4
1 Scope This European Standard describes a procedure for the determination of inorganic arsenic in animal feeding stuffs of marine origin by Solid Phase Extraction (SPE) and Hydride Generation Atomic Absorption Spectrometry (HG-AAS). The method has been successfully tested in a collaborative trial with a working range from 0,19 mg/kg to 2,7 mg/kg (HORRATvalues < 2; HORRAT value is Horwitz –Ratio value). The LOQ of the method is usually approximately 0,1 mg/kg or lower.
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 ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696) EN ISO 6497, Animal feeding stuffs — Sampling (ISO 6497) EN ISO 6498, Animal feeding stuffs — Guidelines for sample preparation (ISO 6498) 3 Principle Inorganic arsenic consists of arsenite, As(III) and arsenate, As(V). This standard describes a method for the determination of inorganic arsenic (i.e. the sum of As(III) and As(V)). A representative test portion of the sample is treated with a diluted hydrochloric acid and hydrogen peroxide solution using microwave assisted heating. Hereby inorganic arsenic species are extracted and As(III) is oxidised to As(V). The inorganic arsenic is selectively separated from other arsenic compounds using solid phase extraction (SPE) and the concentration of inorganic arsenic is determined by HG-AAS in the SPE eluate. The gaseous hydride is transferred into a heated measuring cell (cuvette) by means of a carrier gas stream and decomposed.
Since arsenic (III) and arsenic (V) show a different sensitivity to the hydride technique, it is necessary to reduce arsenic (V) to arsenic (III) in order to avoid incorrect measurements.
WARNING — The use of this 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 standard to establish appropriate safety and health practices and
determine the applicability of regulatory limitations prior to its use. 4 Reagents The concentration of arsenic in the reagents and water used shall be low enough not to affect the results of the determination. All reagents shall be of analytical grade or similar unless otherwise specified. Use water conforming to grade 2 of EN ISO 3696. 4.1 Hydrochloric acid (HCl), mass fraction of ≥ 30 % of approximately
(HCl) ≥ 1,15 g/ml. NOTE Only use hydrochloric acid available with high purity or which was cleaned by a sub-boiling distillation.
4.2 Diluted hydrochloric acid. 4.2.1 0,4 mol/l as eluent for the SPE. Dilute e.g. 20 ml of hydrochloric acid (4.1) to 0,5 l with water. 4.2.2 0,055 mol/l for the extractant solution. SIST EN 16278:2012



EN 16278:2012 (E) 5 Dilute e.g. 5,8 ml of hydrochloric acid (4.1) to 1 l with water. 4.2.3 2,6 mol/l for sample pre-reduction. Dilute e.g. 270 ml of hydrochloric acid (4.1) to 1 l with water. 4.2.4 4,7 mol/l for HG-AAS measurements. Dilute e.g. 500 ml of hydrochloric acid (4.1) to 1 l with water. 4.3 Hydrogen peroxide (H2O2), mass fraction not less than 30 %. 4.4 Extractant solution, volume fraction of 3 % H2O2 in 0,055 mol/l HCl. Dilute e.g. 20 ml hydrogen peroxide (4.3) to 200 ml with 0,055 mol/l hydrochloric acid (4.2.2). 4.5 Acetic acid,
(CH3COOH) = 1,05 g/ml. 4.6 Diluted acetic acid, 0,5 mol/l for washing of SPE columns. Dilute e.g. 15 ml of acetic acid (4.5) to 0,5 l with water. 4.7 Sodium hydroxide pellets, mass fraction of ≥ 98 %. 4.8 Sodium hydroxide, 0,1 mol/l for adjustment of pH. Dilute 0.4 gram sodium hydroxide pellets (4.7) to 100 ml with water. 4.9 Ammonium carbonate, mass fraction of ≥ 99,999 %. 4.10 Ammonium carbonate buffer solution, 40 mmol/l for sample buffering. Dissolve e.g. 0,384 g ammonium carbonate (4.9) in water and dilute to 100 ml with water. 4.11 Methanol (CH3OH), HPLC grade, for conditioning of SPE sorbent. 4.12 Sodium borohydride, mass fraction of ≥ 96 %. 4.13 Sodium borohydride solution for hydride generation. Dissolve e.g. 2,5 g of sodium hydroxide pellets (4.7) in a small amount of water; add 2,5 g of sodium borohydride (4.12) and dilute to 500 ml with water. Prepare a fresh solution daily prior to the hydride generation step and, when necessary, filter before use.
Commercially available sodium borohydride solutions may also be used. NOTE The required concentrations may vary slightly with the system and the instructions of the relevant manufacturer shall therefore be observed. WARNING — It is essential to observe the safety instructions for working with sodium borohydride. Sodium borohydride forms hydrogen with acids and this can result in an explosive air/hydrogen mixture. A permanent extraction system shall be provided at the point where the measurements are carried out.
4.14 L-Ascorbic acid, mass fraction of ≥ 99,7 %. 4.15 Potassium iodide, mass fraction of ≥ 99,5 %. SIST EN 16278:2012



EN 16278:2012 (E) 6 4.16 Pre-reduction solution for sample extract. Dissolve 1,25 g of potassium iodide (4.15) and 1,25 g of L-ascorbic acid (4.14) up to 250 ml with 2,6 mol/l hydrochloric acid (4.2.3). Prepare a fresh solution on the day of analysis. The required concentrations may vary slightly with the system and the instructions of the relevant manufacturer shall therefore be observed. NOTE Addition of a volume fraction of 0,1 % silicone (4.21) to the solution can reduce the formation of foam in the gas-liquid separation system. 4.17 SPE equilibration solution. Mix equal volumes (1+1) of 40 mmol/l ammonium carbonate solution (4.10) with extractant solution (4.4). 2 ml per SPE cartridge is needed. 4.18 Arsenic stock solution. Commercially available standards with a mass concentration of 1 000 mg/l are recommended. Stock solutions in diluted nitric acid are preferred.
4.19 Diluted inorganic arsenic solutions. Dilute the arsenic stock solution (4.18) by water in several steps, such as in the following example: 1 000 mg/l
10 mg/l
1 mg/l
0,1 mg/l 4.20 Calibration solutions. Prepare six external standards including a blank calibration solution that covers the linear range of the element to be determined by diluting the diluted inorganic arsenic solutions (4.19). The linear range is instrument dependent. Appropriate matching of the calibration solutions shall be performed (prereduction according to Table 2). It is important to adjust the acid concentration of the standards to the acid concentration of the samples. The following calibration range is recommended: 0,25 µg/l to 8 µg/l. These calibration solutions should be prepared freshly before use. NOTE
An example on the production of calibration standard is given in Annex B, Table B.2. 4.21 Silicone antifoam agent ≥ 30 %. 5 Apparatus and equipment To minimise contamination, all apparatus and equipment that come into direct contact with the sample and the solutions shall be carefully pre-treated. It is recommended to avoid the use of glassware, since this may cause contamination with arsenate [1]. 5.1 Laboratory grinder, capable of grinding to a particle size of less than or equal to 0,5 mm. 5.2 Analytical balance, capable of weighing to an accuracy of 1 mg. 5.3 Microwave oven with closed vessels, capable of programming temperature. 5.4 pH indicator paper/sticks, for pH range 4 to 7. 5.5 Centrifuge with containers, capable of a minimum centrifuge speed of 4 000 rpm (2 100 g). 1/100 1/10 1/10 SIST EN 16278:2012



EN 16278:2012 (E) 7 5.6 Solid phase extraction cartridges, with strong anion exchange stationary phase. Strata SAX (Phenomenex), 500 mg / 6 ml have proven suitable for the present procedure. (Equivalent SPE columns with similar performance from
...