CORRELATIONS BETWEEN A FLUORIMETRIC and MASS FRAGMENTOGRAPHIC METHOD FOR THE DETERMINATION OF 3‐METHOXY‐4‐ HYDROXYPHENYLACETIC ACID and TWO MASS FRAGMENTOGRAPHIC METHODS FOR THE DETERMINATION OF 3‐METHOXY‐4‐ HYDROXYPHENYLETHYLENE GLYCOL IN CEREBROSPINAL FLUID

Abstract

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.

Cerebrospinal Fluid Measurements Suggest Precursor Availability and Sex Are Involved in the Control of Biogenic Amine Metabolism in a Primate

“…A significant positive correlation was seen between tyrosine and HVA in both females and males ( Table 2 ) , although no such correlation was found in human ventricular CSF (Curzon et al, 1976). However, the human data were obtained using a fluorometric assay for HVA, which has been criticized as the result of a comparison with a gas chromatographic-mass spectrometric method (Muskiet et al, 1979). One interpretation of our finding in vervets is that tyrosine availability is normally involved in the control of dopamine synthesis and it suggests that such a relationship is worth reinvestigating in humans.…”

The Effect of Dexamethasone on Cerebrospinal Fluid Monoamine Metabolites and Cortisol in Psychiatric Patients

“…The fluorometric measurement of amine metabolites in the eSF has several drawbacks as pointed out earlier (19,21). Although it may really be unsuitable to detect fine differences between e.g.…”