EN 15517:2008

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Lebensmittel - Bestimmung von Elementspuren - Bestimmung von anorganischem Arsen in Meeresalgen mit Atomabsorptionsspektrometrie-Hydridtechnik (HGAAS) nach SäureextraktionProduits alimentaires - Dosage des éléments traces - Dosage de l'arsenic inorganique dans les algues marines par spectrométrie d'absorption atomique par génération d'hydrures (SAAGH) après extraction acideFoodstuffs - Determination of trace elements - Determination of inorganic arsenic in seaweed by hydride generation atomic absorption spectrometry (HGAAS) after acid extraction67.050Splošne preskusne in analizne metode za živilske proizvodeGeneral methods of tests and analysis for food productsICS:Ta slovenski standard je istoveten z:EN 15517:2008SIST EN 15517:2009en,fr,de01-april-2009SIST EN 15517:2009SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15517March 2008ICS 67.050 English VersionFoodstuffs - Determination of trace elements - Determination ofinorganic arsenic in seaweed by hydride generation atomicabsorption spectrometry (HGAAS) after acid extractionProduits alimentaires - Dosage des éléments traces -Dosage de l'arsenic inorganique dans les algues marinespar spectrométrie d'absorption atomique par générationd'hydrures (SAAGH) après extraction acideLebensmittel - Bestimmung von Elementspuren -Bestimmung von anorganischem Arsen in Meeresalgen mitAtomabsorptionsspektrometrie-Hydridtechnik (HGAAS)nach SäureextraktionThis European Standard was approved by CEN on 7 February 2008.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© 2008 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15517:2008: ESIST EN 15517:2009

Results of the inter-laboratory tests.11 Bibliography.14
Arsenic compounds are extracted from the sample by diluted hydrochloric acid (in accordance with EN 71-3 [5]) and the arsenic in the extract is determined by hydride generation AAS. In acidic media inorganic compounds of arsenic(III) and arsenic(V) as well as the monomethylarsonic acid (MMA) and dimethylarsinic (cacodylic) acid (DMA) form a volatile hydride with sodium borohydride. There is no reaction of the stable organic arsenic compounds like arsenosugar, arseno-betaine and arseno-choline under these conditions. The gaseous hydride is transferred into a heated measuring cell (cuvette) by means of a carrier gas stream and decomposed. The absorption at 193,7 nm (arsenic line) serves as a measure of arsenic concentration. The hydride signal sensitivity of DMA reaches generally low rates as compared to As(III). The contribution of MMA in the hydride signal can be neglected, since MMA occurs in seaweed only in small amounts. The hydride generation AAS in combination with this hydrochloric acid extraction may be used as nearly selective method of determination for inorganic arsenic. Generation of arsine from As(III) is much faster and gives greater sensitivity than generation from As(V) and is also less subject to interference. Arsenic(V) shall be reduced to arsenic(III) (pre-reduction) in order to avoid incorrect measurements. SIST EN 15517:2009

= (0,07 ± 0,005) mol/l. 4.4 Hydrochloric acid, approximately c = 2 mol/l. 4.5 Sodium borohydride, w ≥ 96 % 4.6 Sodium hydroxide, w ≥ 98 % 4.7 Sodium borohydride solution, e.g. substance concentration c = 2 g/l (example for using the flow injection procedure described under 6.2.1 (b)). Dissolve 2 g of sodium hydroxide pellets in water, add 2 g of sodium borohydride and dilute to 1 000 ml with water. A fresh solution shall be prepared daily and filtered before use. The concentration by mass of the sodium borohydride solution may vary with the system and the instructions of the relevant manufacturer shall therefore be observed. 4.8 Diluted hydrochloric acid, e.g. mass fraction w ≈ 3 % (carrier solution, only for use in the flow injection procedure). Dilute approximately 90 ml of hydrochloric acid (4.2) to 1 000 ml with water. The concentration by mass of the carrier solution may vary with the system and the instructions of the relevant manufacturer shall therefore be observed. 4.9 L-Ascorbic acid, w(C6H8O6) ≥ 99,7 % 4.10 Potassium iodide, w(KI) ≥ 99,5 % 4.11 Potassium iodide/ascorbic acid solution Dissolve 3 g of potassium iodide and 5 g of ascorbic acid in water and dilute to 100 ml. Prepare a fresh solution daily. The concentrations of the potassium iodide and ascorbic acid may vary slightly with the system and the instructions of the relevant manufacturer shall therefore be observed. 4.12 Diarsenic trioxide (As2O3), w(As2O3) ≥ 99,5 % 4.13 Arsenic stock solution, with an arsenic mass concentration of 1000 mg/l. If commercial stock solutions are not available, proceed as follows: dissolve 1,320 g of diarsenic trioxide SIST EN 15517:2009

1000 mg/l →100/5 50 mg/l →50/5 5 mg/l →50/1 0,1 mg/l A standard solution of 5 mg/l arsenic in 0,6 % (mass fraction) hydrochloric acid is stable for at least one week. 4.15 Arsenic calibration solutions Prepare five calibration solutions in the required calibration range from the standard solution of 0,1 mg/l (4.14), ensuring that the concentrations of the calibration solutions are not outside the linear range of the calibration function and are also in the expected sample content range. The concentration of acid in the calibration solutions shall be equal to that in the sample solution. Example for the 1 µg/l to 10 µg/l range:
0,1 mg/l →100/1 1 µg/l
→100/3 3 µg/l
→100/5 5 µg/l
→100/8 8 µg/l
→100/10 10 µg/l The calibration solutions may also be prepared from the appropriately diluted standard solution in the measurement vessel itself by adding the reagents for the pre-reduction (see 6.1.3). Prepare fresh calibration solutions daily. The following procedure is recommended for the preparation of standard and calibration solutions: pour some water into the volumetric flask and add the requisite amount of acid. After cooling to room temperature, add the stock or standard solution using a pipette and dilute to the mark with water. 4.16 Zero member compensation solution, containing water and acid in a concentration equal to that in the sample solution. 5 Apparatus and equipment 5.1 General To minimise the contamination, all apparatus that come into direct contact with the sample and the solutions shall be carefully pre-treated according to EN 13804. SIST EN 15517:2009

5.6 Indicator paper 5.7 Device for thermostating, at approximately 37 °C. 5.8 Stirrer or shaking machine 6 Procedure 6.1 Sample preparation 6.1.1 General It is possible that extracted arsenic compounds are decomposed to inorganic arsenic, even when stored in a refrigerator. Therefore, determination by hydride generation AAS should be conducted as soon as possible, latest within one week. 6.1.2 Hydrochloric acid extraction In imitation of EN 71-3 the well homogenized sample is weighed (minimum weighed portion 0,2 g) into a vessel, which is suitable for the extraction and allows sufficient agitation motion. The ratio of weighed portion to extracting agent (extractant) shall be 1:50 (1 part + 49 parts). Add the appropriate amount of hydrochloric acid solution (4.3) of approximately 37 °C to the sample and mix for 1 min. Transfer one drop of this mixture onto indicator paper. If the pH is more than 1,5, add dropwise hydrochloric acid (4.4) while stirring until the pH value lies between 1,0 and 1,5. Continuously agitate (by stirring or shaking) the suspension at a temperature of approximately 37 °C for 1 h and then allow it to stand for 1 h at approximately 37 °C. Immediately afterwards solids shall be separated from the solution. First centrifuge for 10 min and then filter through a syringe filter (5.5). The extract shall be free of particles. The concentration of arsenic in the solution should be measured by hydride generation AAS as soon as possible. The extraction solution is stored in a suitable vessel in a refrigerator until measurement. 6.1.3 Pre-reduction Depending on the hydride system used, it may be necessary to use larger or smaller volumes than described below. The ratios specified shall, however, be maintained. Introduce and thoroughly mix 2 ml of calibration solution (4.15) and 2 ml of hydrochloric acid (4.2) into the measurement vessel of the hydride system. Then add 1 ml of potassium iodide/ascorbic acid solution (4.11) and again mix thoroughly. After leaving for 45 min at room temperature in an open vessel, dilute to 10 ml with water and mix thoroughly to obtain a solution ready for measuring. If the calibration solution is prepared in the measurement vessel itself, use the appropriate quantity of standard solu
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