A document filtering scheme capable of reducing the number of erroneously selected non-relevant documents without reducing the number of correctly selected relevant documents is disclosed. A hot, gaseous medium is then emitted from at least one discharge or nozzle to thereby shrink the heat shrinkable film on the product unit while simultaneously moving the product unit on a conveying arrangement along a transport path. Also provided is a kit including the device and ancillary instrumentation to facilitate the method of the present invention. Also, the apparatus includes laser sources, a focussing optical system, and a combining optical system. The present apparatus can qualitatively and quantitatively monitor a content of a specific component of a tested solution. Therefore, the process is capable of obtaining a polar olefin copolymer having excellent properties under mild polymerization conditions.