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 isotachophoresis (CITP) and discontinuous buffer systems prior to CZE separation 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 improvement of the concentration detection limit of at least 2 orders of magnitude over that obtainable using the conventional CZE format. Such improvements in sample loadings now enable identification and quantitation of PSP toxins present in dinoflagellate and shellfish extracts using capillary electrophoresis. This preconcentration technique was found to be entirely compatible with electrospray mass spectrometry (ESMS) and permitted the analysis of scallop extracts containing submicromolar levels of PSP toxins. In situations where higher levels of selectivity are required for unambiguous identification of individual PSP toxins, CITP/CZE was combined with tandem mass spectrometry. The ease of operation, flexibility, selectivity, and short analysis time of CITP/CZE/ESMS make this technique an attractive method for the monitoring of PSP toxins.