IDENTIFICATION AND QUANTIFICATION OF GAMMA-GLUTAMYL CONJUGATES OF BIOGENIC-AMINES IN THE NERVOUS-SYSTEM OF THE SNAIL, HELIX-ASPERSA, BY GAS-CHROMATOGRAPHY NEGATIVE-ION CHEMICAL-IONIZATION MASS-SPECTROMETRY

The gamma-glutamyl conjugates of p-octapamine and dopamine were identi fied unambiguously for the first time and quantified in a single cereb ral ganglion or pleural plus pedal ganglia of the snail, Helix aspersa , by gas chromatography-negative-ion chemical ionisation mass spectrom etry. A new method was used for synthesis of gamma-glutamylamine stand ards. The concentration of gamma-glutamyltyramine was found to be low in the tissues, therefore it was used as an internal standard. The gam ma-glutamylamines were extracted with water and derivatised with penta fluoropropionic anhydride and trifluoroethanol. Under negative-ion che mical ionisation conditions, the trifluoroethyl and pentafluoropropion yl derivatives produced significant ions which were sufficiently abund ant to be suitable for selective ion monitoring. The method had a limi t of detection of ca. 80 pg of 7-glutamyl conjugate per tissue and cal ibration curves were linear over the range examined.