- Publication date
- 29 October 2014 (Last updated on: 6 June 2016)
For the determination of selenomethionine in the feed additive:
- reversed phase high performance liquid chromatography with UV detection (RP-HPLC-UV)
- high performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICPMS) after triple proteolytic digestion
For the determination of total selenium in the feed additive:
- inductively coupled plasma atomic emission spectrometry (ICP-AES)
- inductively coupled plasma mass spectrometry (ICPMS)
For the determination of total selenium in premixtures, compound feed and feed materials:
- hydride generation atomic absorption spectrometry (HGAAS) after microwave digestion (EN 16159:2012)
In the current application authorisation is sought for selenomethionine under the category/functional group 3(b) ‘nutritional additives’/‘compounds of trace elements’ according to the classification system of Regulation (EC) No 1831/2003 – Annex I. The product with the trade name SelenoSource AF 2000 is a selenium enriched yeast (Saccharomyces cerevisiae NCYC R645) containing 2000 to 2400 mg total selenium /kg, with a maximum of 2 % of residual inorganic selenium. At least 70 % of the total organic selenium in SelenoSource AF 2000 is in the form of selenomethionine. The product is intended to be incorporated into compound feedingstuffs to obtain a maximum dosage of 0.50 mg total selenium/kg of complete feedingstuffs. Authorisation is sought for the use of the product for all animal species.
For the determination of total selenium in the feed additive, the Applicant submitted a single laboratory validated ICP-AES (inductively coupled plasma – atomic emission spectrometry) method. The method was validated using the selenium enriched yeast Certified Reference Material (SELM-1) from NRC-CNRC, certified for the total selenium content. The method performance characteristics reported by the Applicant and further confirmed by a second independent laboratory, in the frame of a verification study, are: - a recovery rate ranging from 99 to 105 %; - a relative standard deviation for repeatability (RSDr) ranging from 1.1 to 2.7 %; and - a relative standard deviation for intermediate precision (RSDip) ranging from 1.5 to 2.5 %. Based on the acceptable method performance characteristics the CRL recommends the single laboratory validated and verified method for official control to determine total selenium in the feed additive.
For the determination of total selenium in the premixtures and feedingstuffs the Applicant submitted two ring trial validated methods (AOAC method 996.16:2000). Another ring-trial validated method - included in the method collection of VDLUFA (Germany) - is currently being adopted as a CEN standard. The method for the determination of total selenium by hydride generation atomic absorption spectrometry (HGAAS) after microwave digestion is based on the extraction with 65 % nitric acid and 30 % H2O2. The following reproducibility relative standard deviations (RSDR) are reported: - RSDR = 7.3 % for premixtures containing 112 mg Se/kg; and RSDR = 7.4 % for feedingstuffs containing 0.48 mg Se/kg. The limits of quantification are clearly below the legal limit of 0.5 mg Se/kg feed. The CRL-FA recommends this dedicated Draft CEN method for official control to determine total selenium in premixtures and feedingstuffs.
Upon request from EFSA, the EURL evaluated two single-laboratory validated and further verified analytical methods, for the determination of selenomethionine in the feed additive (selenium enriched yeast - SelenoSource AF 2000), based on: - reverse phase high performance liquid chromatography with UV detection (RP-HPLC-UV); and – high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICPMS) after triple proteolytic digestion. The following performance characteristics of the RP-HPLC-UV method were reported in frame of validation and verification studies: - a relative standard deviation for repeatability (RSDr) ranging from 1.3 to 2.0 %; - a relative standard deviation for intermediate precision (RSDip) ranging from 0.8 to 3.2 %; and - a recovery rate (Rrec) ranging from 95 to 105 %. Similar performance characteristics were obtained for the HPLC-ICPMS method: - RSDr ranging from 2.6 to 4.3 %; - Rrec ranging from 98 to 104 %. This method was previously recommended by the EURL evaluation report in the frame of FAD-2009-0029 and FAD-2010-0044 dossiers for the determination of selenomethionine in the feed additives. Based on the acceptable method performance characteristics the EURL recommends the two methods mentioned above for official control to determine selenomethionine in the feed additive.
No further testing or validation is required.