Sample preparation method using a cartridge (Sep-Pak Plus Long) in which 2ml of a superior adsorbent CSP800 was packed was optimized for convenient and quantitative Ames mutagenicity assay of tap water.
Mutagenicity activities were decreased considerably by free chlorine reduction by sodium sulfite. Recovery of mutagens from tap water augmented much in lower pH. There was no influence of adsorbing flowrate in the range from 8 to 80ml·min-1 on the recovery of mutagens. Therefore, it is optimal that tap water adjusted at pH2 without free chlorine reduction is fed to the cartridge at a flowrate of c.a. 50ml·min-1. By this method, the mutagens less than 8,000 net revertants.·l-1 could be recovered completely from 2l of water sample, and those more than that could be recovered from 1l. The adsorbed mutagens could be desorbed by 2ml-dimethyl sulfoxide (DMSO) at 0.15 ml·min-1 in upper flow.
This newly developed method requires only 1 or 2l of water sample and less than an hour to concentrate mutagens with over 90% recovery. Furthermore, the desorbing DMSO solution can be used directly to Ames assay without solvent exchange, because concentration factor of mutagens by this method attains 500 or 1,000 times.
