The present invention relates to a preconcentrator for vapors and particles collected from air. The vapor preconcentrator is made from plural layer of coils. The coil is made of resistance alloy. The pitch size of the coil is made to precisely trap/filter out certain size of the particles during preconcentration. Multiple coils could be made with different pitch sizes to achieve multiple step filtrations. When the sample flow enters the preconcentrator chamber, it passes through the coils. The particles of different sizes are trapped on different layer of coils. The vapor sample can be trapped on any coils when interacted with the coil surface. They could be trapped without any affinitive coating as the preconcentrator is at relatively low temperature. Different coils or different sections of the coil can be coated with different material to trap chemicals of different classes. During the desorption process, the coils are flash heated with controlled temperature ramping speed to evaporate the trapped chemicals. Various configurations, constructions, and methods of operation are presented.