Determination of tetramine in marine gastropods by liquid chromatography/electrospray ionization-mass spectrometry.

Tetramine (tetramethylammonium ion) is found at high levels (several mg/g) in the salivary gland of buccinid gastropods and has been involved in numerous poisoning incidents after ingestion of those gastropods. A sensitive and selective determination method for tetramine, which is based on a combination of liquid chromatography (LC) and electrospray ionization-single quadrupole mass spectrometry (ESI-MS), was developed. Following separation by LC on a cation-exchange column, tetramine was easily detected by simultaneous monitoring of a molecular ion (m/z 74) at a cone voltage of 30 V and a fragment ion (m/z 58) at 70 V. A linear calibration curve was obtained in the range of 0.1-100 ng by plotting the peak areas of the molecular ion versus the amounts of tetramine. Spiking experiments demonstrated that tetramine in gastropod tissues can be determined by the LC/ESI-MS method, without being affected by sample matrices as well as the extration procedure. Applications of the new method to gastropod samples revealed that a small amount of tetramine is contained even in mid-gut gland and muscle and that tetramine in the salivary gland diffuses to other tissues during boiling and slow thawing.