This document specifies a general method for the determination of the micronutrients complexed by complexing agents in organo-mineral fertilizers. The method allows the determination of the total concentration of each complexed micronutrient in complexes after subtraction of the chelated micro-nutrients content, but it does not identify the individual complexing agents. This procedure concerns EU organo-mineral fertilizing products which contain complexed micro-nutrients covered by Regulation (EU) 2019/1009 [6]. The method is applicable to a mass fraction of the metal complexed of at least 0,07 %, 0,006 % and 0,035 % of Fe, Mn and Zn respectively (see [7]). A lower limit of quantification has not been established for Cu and Co.