This document specifies a method for the determination of arsenic (As), cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb), nickel (Ni) and zinc (Zn) in aqua regia plant biostimulant digests using inductively coupled plasma-atomic emission spectrometry (ICP-AES). This document is applicable to the fertilizing product blends belonging to PFC 7 where the EU fertilising product plant biostimulant contained in the blend represents the highest % by mass in the blend. In case of equal shares, the user can apply either this or the standard(s) applicable to the other component product(s). This method is applicable to aqua regia digests prepared according to EN 17701-1: 1. The method can be used for the determination of other elements, provided the user has verified the applicability. NOTE Alternatively, inductively coupled plasma mass spectrometry (ICP-MS) can be used for the determination of the elements in the aqua regia digests if the user proves that the method gives the same results.