This invention relates to a sample holder for isolating magnetically labelled particles from a non-magnetic medium in a plurality of samples. The holder comprises a magnetic base for applying a magnetic force to the magnetically labelled particles and a body which is mountable on the base and demountable therefrom. The body comprises an array of sample holding portions and a magnetizable member which is magnetically urged towards the magnetic base when the body is seated on the base, whereby the body is urged to remain seated on the base. The invention also relates to use of the sample holder to separate magnetic particles from a non-magnetic medium and methods of performing such a separation.