Separation of the enzyme cofactor pyrroloquinoline quinone and three isomeric analogues by capillary electrophoresis with ion-pairing media

The enzyme cofactor pyrroloquinoline quinone (PQQ) was successfully separat ed from three closely related isomeric analogues by capillary electrophores is with ultraviolet detection. Rapid and efficient separation of all four n egatively charged isomers with baseline resolution was achieved by the addi tion of low concentrations (1-5 mM) of short chain tetraalkylammonium (TAA) salts to the capillary buffer. The TAA cations act as ion-pairing agents a nd promote differential migration of the isomers with only a minimal reduct ion in the electroosmotic flow. The effects of the TAA salt concentration a nd the alkyl chain length were examined. Detection limits of PQQ and its is omers were in the range of 7-15 mu M with mass detection limits of 98-210 f mol. (C) 2000 Elsevier Science B.V. All rights reserved.