IMPROVEMENT IN DETECTION LIMITS FOR THE DETERMINATION OF PARALYTIC SHELLFISH POISONING TOXINS IN SHELLFISH TISSUES USING CAPILLARY ELECTROPHORESIS ELECTROSPRAY MASS-SPECTROMETRY AND DISCONTINUOUS BUFFER SYSTEMS

The application of on-column sample preconcentration with capillary is otachophoresis (CITP) and discontinuous buffer systems prior to CZE se paration has been investigated for the analysis of paralytic shellfish poisoning (PSP) toxins. A judicious choice of leading and terminating electrolytes for the preconcentration step has provided an improvemen t of the concentration detection limit of at least 2 orders of magnitu de over that obtainable using the conventional CZE format. Such improv ements in sample loadings now enable identification and quantitation o f PSP toxins present in dinoflagellate and shellfish extracts using ca pillary electrophoresis. This preconcentration technique was found to be entirely compatible with electrospray mass spectrometry (ESMS) and permitted the analysis of scallop extracts containing submicromolar le vels of PSP toxins. In situations where higher levels of selectivity a re required for unambiguous identification of individual PSP toxins, C ITP/CZE was combined with tandem mass spectrometry. The ease of operat ion, flexibility, selectivity, and short analysis time of CITP/CZE/ESM S make this technique an attractive method for the monitoring of PSP t oxins.