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Comparison of high-performance liquid chromatography with electrochemical detection and gas chromatography-mass fragmentography for the assay of salsolinol, dopamine and dopamine metabolites in food and beverage samples.

High-performance liquid chromatography with electrochemical detection (HPLC-ED) and combined gas chromatography--mass spectrometry in the single-ion monitoring mode (GC--MS-SIM) have been used for the determination of salsolinol, dopamine, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxyphenylethanol and norepinephrine in a selection of food and beverage samples. The unique specificity of the SIM mode allows a simple one-step extraction to be used even for complex sample matrices. We have been able to demonstrate the quantitative and qualitative advantages offered by GC--MS over HPLC--ED by direct comparison of the chromatographic data obtained. We demonstrate that the specificity of SIM and the benefits offered by the incorporation of deuterated internal standards make GC--MS-SIM the method of choice for valid identification and precise quantitation of salsolinol, dopamine and dopamine metabolites in a complex sample matrix.

The alkaloids ofBeilschmiedia elliptica

The isolation of the major alkaloid of the bark of Beilschmiedia elliptica is described and its structure determined as l,9-dihydroxy-2,l0-dimethoxynoraporphine (IIIb). This is an amendment of the structure originally proposed for this base. Of the alkaloids present in the leaves of this species one was identified as isoboldine, the N-methyl derivative of laurelliptine.

Novel magnetic circular dichroism spectra of monoacetyl porphyrins. Structure implications.

Abstract The unexpected observation of a pair of oppositely signed MCD bands within the Q x O transition of monoacetyl porphyrins is related to the existence of equilibria between NH proton tautomers and/or confomational populations of the acetyl substituent.

Secondary amines isolated from venom gland of dolichoderine antTechnomyrmex albipes

A series of unsaturated secondary amines have been isolated from the dolichoderine antTechnomyrmex albipes (F. Smith). The major components of the mixture have been shown by spectroscopic procedures to be dinon-8-enylamine, andN-hept-6-enylnon-8-enamine, and these structural assignments have been confirmed by synthesis. Mass spectrometry indicates the presence of trace amounts of the bis C11 amine and the C9-C11 amine. The four amines, present in total at approximately 2.8μg/ant, are located in the gaster of the insect in a gland that is considered to be the venom gland although it is atypical from a morphological standpoint.

Synthesis of petroporphyrins with six and seven membered exocyclic ring systems

Intramolecular cyclization of porphyrins substituted with either propanoic or butanoic acid side chains led to the formation of the cyclic ketones (3c) and (4d) from which the petroporphyrins (3b) and (4c) were obtained; treatment of (4c) under acidic conditions did not result in rearrangement of the seven membered exocyclic ring.

Cytochrome C oxidase: isolation, crystallisation, and synthesis of porphyrin a dimethyl ester

Haem A preparations from beef heart are found to be heterogeneous and demetallation yields a polar porphyrin together with porphyrin A, isolated as its crystalline dimethyl ester (2) which is studied spectroscopically and its structure confirmed by unambiguous synthesis.

Synthesis of the methyl ester of the magnesium-free derivative of chlorophyll c2

The synthesis is reported of 7′,7″-dehydro-2,4-dide-ethyl-2,4-divinylphaeoporphyrin a5 dimethyl ester (1c) which is the methyl ester of the magnesium-free derivative of chlorophyll c(1b).