Assigning of the UN classification depends on the chemical composition of the toner/ ink preparation. 

E.g. certain toners (e.g.  CE505A) contain materials such as Ferrite that have magnetic properties. Hence these toners are assigned the UN code 2807 for magnetized material. On the other hand, toners in SKUs such as CF400A or CF403A do not contain the ferrite material and therefore do not carry the UN magnetized material classification. 

Please see also Are HP supplies classified as Dangerous Goods Magnetized Material or UN2807?