EN 16159:2012

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.PHWULMRFuttermittel - Bestimmung von Selen mit Atomabsorptionsspektrometrie-Hydridtechnik (HD-AAS) nach Mikrowellen-Druckaufschluss (Aufschluss mit 65 % Salpetersäure und 30 % Wasserstoffperoxid)Aliments pour animaux - Dosage du sélénium par spectrométrie d'absorption atomique par génération d'hydrures (SAAGH) après digestion par micro-ondes (extraction avec de l'acide nitrique à 65 % et du peroxyde d'hydrogène à 30 %)Animal feeding stuffs - Determination of selenium by hydride generation atomic absorption spectrometry (HGAAS) after microwave digestion (digestion with 65 % nitric acid and 30 % hydrogen peroxide)65.120KrmilaAnimal feeding stuffsICS:Ta slovenski standard je istoveten z:EN 16159:2012SIST EN 16159:2012en,fr,de01-april-2012SIST EN 16159:2012SLOVENSKI
STANDARD
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16159
February 2012 ICS 65.120 English Version
Animal feeding stuffs - Determination of selenium by hydride generation atomic absorption spectrometry (HGAAS) after microwave digestion (digestion with 65 % nitric acid and 30 % hydrogen peroxide)
Aliments pour animaux - Dosage du sélénium par spectrométrie d'absorption atomique par génération d'hydrures (SAAGH) après digestion par micro-ondes (extraction avec de l'acide nitrique à 65 % et du peroxyde d'hydrogène à 30 %)
Futtermittel - Bestimmung von Selen mit Atomabsorptionsspektrometrie-Hydridtechnik (HD-AAS) nach Mikrowellen-Druckaufschluss (Aufschluss mit 65 % Salpetersäure und 30 % Wasserstoffperoxid) This European Standard was approved by CEN on 30 December 2011.
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.
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Results of the inter-laboratory test . 12Annex B (informative)
Flowchart - Determination of selenium by hydride generation atomic absorption spectrometry (HGAAS) after microwave digestion (digestion with 65 % nitric acid and 30 % hydrogen peroxide . 13Annex C (informative)
Alternative digestion procedure with the same digestion efficiency: Acid digestion with a mixture of 65 % nitric acid and 70 % perchloric acid (7:3 by volume) at atmospheric pressure . 14C.1Preparation of selenium calibration solutions . 14C.2Preparation of the test solution . 14C.3Measurement of the test solution . 15C.4Ten rules for automated wet ashing with perchloric acid . 15Bibliography . 16 SIST EN 16159:2012

The method was successfully tested by an inter-laboratory study of CEN/TC 327/WG 4 in the range of 0,25 mg/kg to 74 mg/kg. The limit of quantification is 0,5 µg/l of the test solution which corresponds to the calibration standard 2. Using a test portion of 0,5 g and a volume of the test solution of 25 ml after pressure digestion the limit of quantification is calculated as 0,125 mg/kg in the feed material. NOTE A lower limit of quantification could be achieved – each laboratory has to prove it.
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) prEN ISO 6498, Animal feeding stuffs  Guidelines for sample preparation (ISO/DIS 6498) 3 Principle Selenium is determined in the test solution by hydride generation atomic absorption spectrometry (fluorescence hydride generation atomic absorption) after microwave pressure digestion and a pre-reduction step.
The homogenised feeding stuff test sample is digested by nitric acid and hydrogen peroxide under pressure and high temperatures in a microwave-heated pressure digestion system.
Selenium ions of the test solution are reduced with hydrochloric acid to selenium (IV) and converted to selenium hydride (SeH2) by sodium borohydride. This selenium hydride is transferred by a gas stream to a heated measurement cell and decomposed. The absorption at the selenium line at 196,0 nm corresponds to the amount of selenium. NOTE Selenium (VI) is not determined by the hydridisation as described here. It is therefore necessary to adjust the digestion conditions and to exercise a pre-reduction step with hydrochloric acid to yield only selenium (IV).
Other digestion procedures with the same digestion efficiency or other measurement systems like Fl-HGAAS or hydride generation inductively coupled plasma optical emission spectrometry are possible (see Annex C). 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 use. SIST EN 16159:2012

NOTE High purity is essential to avoid potential contamination. Therefore, only use reagents available with high purity or perform an extraction by a sub-boiling distillation for nitric acid (4.1). 4.1 Nitric acid, not less than 65 % (mass fraction), of approximately
(HNO3) = 1,4 g/ml. 4.2 Diluted nitric acid, mix 100 ml nitric acid (4.1) with water to 1 l. 4.3 Hydrogen peroxide, not less than 30 % (mass fraction), of approximately
(H2O2) ≥ 1,1 g/ml. 4.4 Hydrochloric acid, 30 %, mass concentration of approximately
(HCl) = 1,15 g/ml. 4.5 Diluted hydrochloric acid, e.g. about 3 % (mass fraction), as carrier solution for the use in the flow-injection-procedure. EXAMPLE Dilute approximately 90 ml of hydrochloric acid (4.4) to 1 l with water. 4.6 Sodium borohydride solution, e.g. c = 2 g/l. Dissolve 2 g of sodium hydroxide pellets in water, add 2 g of sodium borohydride and dilute to 1 000 ml with water into 1 000 ml flask (5.3). Prepare a fresh solution daily and, when necessary, filter before use. When the analysis procedure takes longer, it is recommended to cool the sodium borohydride solution, i.e. with ice around the flask, during its use in the HGAAS measurement.
NOTE 1 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.
NOTE 2 Sodium borohydride, stable aq. solution, 4,4 mol/l in 14 mol/l NaOH is also commercially available. 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 measurements are carried out. 4.7 Selenium stock solution, c (Se) = 1 000 mg/l. The stock solution is commercially available. It is advisable to use certified stock solutions. Otherwise, dissolve 1,4053 g of selenium dioxide (SeO2) and 2 g sodium hydroxide in approximately 50 ml water, and dilute to 1 000 ml with water. 4.8 Selenium standard solution, c (Se) = 1 mg/l. Dilute e.g. 100 µl of the stock solution (4.7) in a 100 ml flask (5.3) to give a concentration of 1 mg/l. The selenium standard solution shall contain an adequate amount of hydrochloric acid, e.g. 2 ml of hydrochloric acid (4.4) per 100 ml.
NOTE The standard solution is stable for at least three months. 4.9 Selenium calibration solutions. SIST EN 16159:2012
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