Four new polymeric oxa-thiacrown ethers were prepared by the intramolecular cy-clization of poly (2-chloroethylglycidyl ether) with dimercaptans, which is the m
Introduction Since it was found that cetyltrimethylammonium bromide (CTMAB) can increase greatly the sensitivity of the tin (Ⅳ)-pyrocatechol violet (PV) system