Microchip electrophoresis with amperometric detection for the study of the generation of nitric oxide by NONOate salts

Abstract

Microchip electrophoresis (ME) with electrochemical detection was used to monitor nitric oxide (NO) production from diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA/NO) and 1-(hydroxyl-NNO-azoxy)-L-proline disodium salt (PROLI/NO). NO was generated through acid hydrolysis of these NONOate salts. The products of acid hydrolysis were introduced into a 5-cm separation channel using gated injection. The separation was accomplished using reverse polarity and a background electrolyte consisting of 10 mM boric acid and 2 mM tetradecyltrimethylammonium bromide, pH 11. Electrochemical detection was performed using an isolated potentiostat in an in-channel configuration. Potentials applied to the working electrode, typically higher than +1.0 V vs. Ag/AgCl, allowed the direct detection of nitrite, NO, DEA/NO, and PROLI/NO. Baseline resolution was achieved for the separation of PROLI/NO and NO while resolution between DEA/NO and NO was poor (1.0 ± 0.2). Nitrite was present in all samples tested.