 Next, we incise the wall of the remaining three straws along almost their whole length. That is, the cutting starts approximately 6-8 mm from one end and in one steady move is continued until the other end of the straw is reached. A sharp and clean scalpel blade should be used. The incision should be as smooth as pos-sible, torn edges should be avoided-they are likely sources of additional magnetic signals, which makes such a straw useless as the sample holder;