SEPARATION OF POLYPHOSPHATES AND POLYCARBOXYLATES BY CAPILLARY ELECTROPHORESIS IN A CARRIER ELECTROLYTE CONTAINING ADENOSINE 5'-TRIPHOSPHATE AND CETYLTRIMETHYLAMMONIUM BROMIDE WITH INDIRECT UV DETECTION

A capillary electrophoresis method was developed for the separation of polyanions of environmental concern, such as polyphosphates [ortho- ( P-1), pyro- (P-2) and tripoly- (P-3)] and polycarboxylic acids (nitril otriacetic acid, ethylenediaminetetraacetic acid, diethylenetriaminepe ntaacetic acid and citrate) which are used as builders in detergents. A carrier electrolyte consisting of adenosine 5'-triphosphate as the U V chromophore for indirect detection at 260 nm and cetyltrimethylammon ium bromide as modifier to reverse the electroosmotic flow was used. T he changes in the effective mobilities of some solutes and common UV c hromophores with pH were either predicted theoretically or determined experimentally. Differences in effective mobilities of the solutes wer e used to optimize the pH for their separation. Baseline separation fo r all of the solutes was achieved. Detection limits for all of the sol utes were in the range 2 . 10(-5)-5 . 10(-5) M. Application of the dev eloped method to real samples was demonstrated by separation and deter mination of polyphosphates (P-1, P-2 and P-3) in a commercial detergen t. For sample preparation, only simple dilution with water and filtrat ion were needed.