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Abstract— The effects of electrothermic destruction and electrical stimulation of the locus coeruleus on the brain levels of vanillylmandelic acid (VMA), 3‐methoxy‐4‐hydroxyphenylglycol (MOPEG) and noradrenaline (NA) were studied in the rat. Fourteen days after destruction of the locus coeruleus, the content of NA in the hippocampus and that of MOPEG in the rest of the brain were decreased by more than 70% and 50% respectively. Stimulation of the locus coeruleus induced a decrease in hippocampal levels of NA of 38%, while MOPEG levels were found to be increased more than 3‐fold After intraventricular injection of 1 μg of adrenaline (A), the levels of MOPEG were Substantially increased In none of these experiments was any variation in VMA levels found, These results suggest that in the rat brain endogenous VMA is not a metabolite of either NA or A The formation of MOPEG from A as well as from NA appears to be possible.

The preparation of some deuterium labelled catecholamines, catecholamine metabolites and tryptophan metabolites is described. 4Simple exchange reactions in DCl/D 0 solution or reductions with Li A1 D were used. The deuterium labelled compounds prepared are suitable for use as internal standards for quantitative mass-fragmentographic analysis of their unlabelled analogs in biological material. Mass spectra of trimethylsilyl and trimethylsilyl-N-trifluoroacetyl derivatives of 2,5,6-trideutero vanillactic acid, I,l-dideutero-l-hydroxy-2(2,5,6-trideutero catecho1)ethane, 2,5,6-trideutero epinephrine, 2,5,6-trideutero norrnetanephrine and hexadeutero indole-3-acetic acid are given together with those of their naturaloccurring analogs. 2 The mass-fragmentographic determination of small amounts of biogenic amines and their metabolites in biological material has become of increasing interest in the past few years ( 1 -7 ) . The method combines both specificity and sensitivity and can achieve a high degree of precision with the use of analogs labelled with stable isotopes as internal standards. Howevel; these compounds are not always commercially available, or are unsatisfactory because 0 1970 by John Wiley & Sons L t d .

Quinine can easily be determined in soft drinks by means of reversed-phase ion-pair chromatography. Sample preparation is not necessary. Quinine is detected by fluorescence and UV spectrophotometry by continuous monitoring of the column effluent. A rectilinear response is obtained in the concentration range of 20--100 mg/l. The complete assay procedure takes about 8 min.

One‐hundred and twenty‐two lumbar cerebrospinal fluid (CSF) samples were assayed for 3‐methoxy‐4‐hydroxyphenylacetic acid (HVA) by both a fluorimetric and mass fragmentographic method. The correlation coefficient (cc) and residual standard deviation (Syx) of the results were calculated as 0.966 and 23.3 ng/ml, respectively. If only samples containing less than 100ng/ml of HVA were considered, somewhat different values for cc and Syx were found (0.854 and 10.0 ng/ml, respectively). The data obtained by the fluorimetric method were consistently 17% lower than those obtained by the mass fragmentographic method. Spiking experiments resulted in 96.5 ± 7.8% recovery for the fluorimetric method, whereas the use of a deuterated internal standard was found to compensate completely for losses in the mass fragmentographic method. In addition the correlation between two different mass fragmentographic methods for the simultaneous determination of HVA and 3‐methoxy‐4‐hyd‐roxyphenylethylene glycol (MOPEG) in CSF was studied. The measurements were performed in different laboratories and resulted in correlation coefficients of 0.941 and 0.940 and residual standard deviations of 7.6 and 1.0 ng/ml for HVA and MOPEG, respectively. From all data we conclude that mass fragmentographic methods for the determination of catecholamine metabolites in CSF are superior to fluorimetric methods because of their selectivity, reproducibility and accuracy.