As a tool to determine the magnetic susceptibility of a nano/microparticle in a liquid, a nano-gap magnetophoresis device was fabricated using tilted flat glass plates and a permanent magnet. The nano-gap device was not only used to determine the size of particles, but also directly provided measurements of Raman spectra of fractionally trapped particles in the nano-gap device. The performance of the new hyphenated method was demonstrated by an analysis of suspended particle matter in traffic air.