Analysis of tetramine in sea snails by capillary electrophoresis-tandem mass spectrometry

Abstract

Tetramine (tetramethylammonium ion) is an autonomic ganglionic blocking agent that is found in several marine gastropod species. It is responsible for numerous incidents of human intoxication in Japan, Europe and Canada, due to the consumption of whelks (sea snails). This communication reports on a capillary zone electrophoresis-mass spectrometry (CZE-MS) method for the detection and quantitation of tetramine in whelk tissues. The interfacing of CZE and MS was accomplished with a coaxial sheath flow arrangement and pneumatically assisted electrospray ionization. CZE separations were evaluated using both bare fused-silica columns and capillaries coated with linear polyacrylamide, with the latter showing the better performance. Enhanced selectivity for trace level detection of tetramine in tissue extracts was achieved using CZE with on-line tandem mass spectrometry (CZE-MS-MS). Quantitation of the target analyte was facilitated using tetraethylammonium ion as an internal standard. The method has been applied to the analysis of two different Neptunea whelk species from Canada ( N. decemcostata and N. despecta tornata) and one from Japan ( N. arthritica). The analysis of one sample, implicated in a recent poisoning incident in Labrador, revealed high levels of tetramine (430 μg/g) as well as choline and an unusual choline derivative. This CZE-MS methodology should be useful for a number of other related cholinergic analogs bearing the quaternary amine function.