a method of cleaning a pin head or other implements between handling a plurality of samples of nucleic acid subject to an amplification process using a biochemical amplification product . the method comprises exposing the pin head or other implement to ultraviolet and preferably also infrared illumination between handling different samples in order to suppress cross - contamination by non - specific amplification . the biochemical amplification product may be obtained from a rolling circle amplification procedure , such as that catalyzed by bacteriophage phi29 , or a polymerase chain reaction amplification product .