Iron(III) citrate chelate - 4d22

In the current application authorisation is sought under Article 4(1) for ferric citrate chelate under the category/ functional group (4 b, d) "zootechnical additives"/ "gut flora stabilisers", "other zootechnical additives", according to the classification system of Annex I of Regulation (EC) No 1831/2003. Specifically, authorisation is sought for the use of the feed additive for suckling/weaned piglets and minor porcine species. 

The feed additive (ferric citrate chelate) is an orange-brown powder containing of 16.5 to 20 % (w/w) of iron (III) and a maximum of 3 % (w/w) of iron (II). In addition and on request of the EURL, the Applicant provided the content of total iron ranging from 16.5 to 23 % (w/w) and the content of citrate ranging from 50.2 % to 58.6 % (w/w) in the feed additive. Additionally, the Applicant has set a criterion for citrate content in the feed additive, expressed as the ratio of the percentage of citrate and of total iron, ranging from 2.3 to 3.2. According to the Applicant the active substance of the feed additive is ferric citrate. The feed additive is intended to be incorporated into premixtures and feedingstuffs with a proposed minimum ferric citrate chelate content of 500 mg/kg feedingstuffs. 

For the determination of the ferric citrate content added to premixtures and feedingstuffs the Applicant proposed an indirect single-laboratory validated and verified method, based on the enumeration of colour coated graphite particles (a non-nutrient marker) which are included in the feed additive. For the quantification of the ferric citrate content added to premixtures, the Applicant suggested applying this enumeration method after diluting the premixture samples with blank feed. The following performance characteristics were reported in the frame of the homogeneity study: a relative standard deviation for repeatability of 12.5 % and an average recovery of 86 %, which were considered acceptable by the EURL. 

Based on the available performance characteristics, the EURL recommends for official control this indirect method (using a non-nutrient marker as proposed by the Applicant) for the quantification of the added content of ferric citrate in premixtures and feedingstuffs provided that the following criteria are fulfilled: (1) the marker is well characterised; (2) the marker is added into the feed additive before the mixing of the product with the compound feed; and (3) the inclusion content of the marker, expressed as number of graphite particles per mass of the feed additive, is specified and kept constant (e.g. 72 particles /mg micro-tracered feed additive in the case of 10 % addition rate of the marker into the feed additive). Moreover, it is recommended that these conditions are included in the Regulation authorising the feed additive. In addition, the official control for quantification of the added content of ferric citrate in premixtures and feedingstuffs is not possible when the specific marker is used also for another feed additive(s), in case both (all) are added to the same feed.

For the identification/characterisation of the feed additive, the Applicant proposed to quantify total iron and citrate in the feed additive. For the quantification of total iron the Applicant submitted three internationally recognised ring-trial validated CEN methods: the EN 15510 method based on inductively coupled plasma-atomic emission spectrometry (ICP-AES) after ashing or wet digestion with hydrochloric acid, the EN 15621 method based on ICP-AES after pressure digestion and the EN ISO 6869 method based on atomic absorption spectrometry. These methods were previously evaluated and recommended by the EURL in the frame of the iron group dossier for the quantification of total iron in different feed additives. 

Based on the acceptable performance characteristics available, the EURL recommends for official control of the content of total iron in the feed additive the three ring-trial validated methods described in EN 15510, EN 15621 and ISO 6869. 

For the quantification of citrate in the feed additive the Applicant submitted a single-laboratory validated and further verified method based on ion-exchange high performance liquid chromatography (HPLC) coupled to ultraviolet (UV) detection to quantify citrate in the feed additive. The following performance characteristics were reported in the frame of validation and verification studies: a relative standard deviation for a repeatability (RSD_r) ranging from 0.3 to 0.4 %; a relative standard deviation for intermediate precision (RSD_ip) ranging from 0.3 to 1.6 %; and a recovery rate of 99 %. 

Based on the available performance characteristics the EURL recommends for official control of the content of citrate in the feed additive the single-laboratory validated and further verified method based on ion-exchange high performance liquid chromatography (HPLC) coupled to ultraviolet (UV) detection. 

Further testing or validation of the methods to be performed through the consortium of National Reference Laboratories as specified by Article 10 (Commission Regulation (EC) No 378/2005, as last amended by Regulation (EU) 2015/1761) is not considered necessary.

Recommended Method

as of:

- Commission Implementing Regulation (EU) 2021/1412

For the quantification of total iron in the feed additive:

— inductively coupled plasma-atomic emission spectrometry, ICP-AES (EN 15510); or 

— inductively coupled plasma-atomic emission spectrometry, ICP-AES with pressure digestion (EN 15621)

For the quantification of citrate in the feed additive:

— ion-exchange high performance liquid chromatography (HPLC) coupled to ultraviolet (UV) detection

For the determination of the added content of iron(III) citrate chelate in premixtures, compound feed and feed materials:

— enumeration of colour coated particles of the microtracer present at fixed mass ratio in the feed additive