Patent ID: 7932100

Claim:
A method for detecting a target substance in a sample solution, comprising: a first step of preparing a detecting element comprising a detecting part and a non-detecting part, and a magnetic label including the target substance, the detecting part including a primary capturing body on the surface thereof; a second step of capturing the target substance of the magnetic label with the primary capturing body; and a third step of detecting the magnetic label present in the vicinity of the detecting part, wherein the surface potential ψ 1 of the magnetic label in the second step, the surface potential ψ 2 of the detecting part, and the surface potential ψ 3 of the non-detecting part satisfy any one of the following relationships i) to iv) by forming a layer on a surface of at least one of the magnetic label, the detecting part, and the non-detecting part in the first step: ψ 1 ψ 3 >0 and ψ 2 =0, i) ψ 1 ψ 2 <0 and ψ 3 =0, ii) ψ 1 ψ 2 <0, ψ 2 ψ 3 >0, and |ψ 2 |>|ψ 3 |, and iii) ψ 1 ψ 2 <0 and ψ 2 ψ 3 <0, and iv) wherein the magnetic label and the non-detecting part each have a layered structure, and the outermost layer of the layered structure forming the magnetic label and the outermost layer of the layered structure forming the non-detecting part are made of the same material.