The cyclic voltammometric behavior of epinephrine, norepinephrine, dopamine, epinine, alpha-methyldopamine, beta-methyldopamine, beta-methylepinine, and beta-methoxyepinine has been examined in order to evaluate substituent effects on cyclization rates of the electrochemically generated quinones. We observed that alpha and beta substituents caused a modest enhancement of cyclization rates while an N-methyl group dramatically increased cyclization rates. No correlation was observed between calculated amine pKa values, suggesting that differences in cyclization rates between the primary and secondary amine series were due to inherent nucleophilicity, a measure of which would be gas-phase proton affinities. The acute pressor effects of the newly synthesized catecholamines were compared with the native amines.

Gas chromatography/mass spectrometry techniques uslng chemlcal lonlratlon and electron Impact have been employed to conflrm the presence of ethylene dlbromlde In frults and gralns determlned by electron capture detection gas chromatrography. Interferences from both the solvent and coextractables have been mlnlmlzed to permlt a determlnatlon uslng only two Ions detected In the correct experlmental lntenslty ratlo belonging to the monobromoethylene carbonlum fragment Ion. A complementary measurement under negative Ion methane chemlcal lonlratlon has determlned the bromide Ion to be present.

During a 5 year period from 1982 to 1986, the FDA Los Angeles District Laboratory analyzed 19 851 samples of domestic and imported food and feed commodities for pesticide residues. A single, rapid, multiresidue method was used. The resultant data have been compiled showing the commodities sampled and the identity and range of levels of pesticide residues detected, including an indication of those residue findings that did not comply with U.S. federal tolerance levels. The residue data presented should not be viewed as being representative of the U.S. food supply; rather, the results are indicative of a surveillance- and compliance-oriented sampling of various food shipments collected by the Los Angeles District.

Nearly 20 000 samples of food and feed commodities were analyzed for pesticide residues by the U.S. Food and Drug Administration Los Angeles District Laboratory during the 5-year study period 1981- 1986. The resultant data base has been summarized to provide separate residue information for domestic and imported samples. The overall violation rates for domestic and imported samples collected on a surveillance basis were 3.0 and 2.6%, respectively. For domestic and imported samples collected on a compliance basis, the overall violation rates were 19.7 and 17.5%, respectively.

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