Mass fragmentographic analysis of homovanillic acid and its homoiso analogue in cerebrospinal fluid using the α-dideutero acid as internal standard

The preparation and use of HVA-d₂ for the mass fragmentographic determination of HVA levels in the CSF was described. Following extraction and synthesis of the methyl ester heptafluorobutyryl derivatives samples were injected into a combined gas chromatograph-mass spectrometer connected to a multiple ion detector. The two fragments set into focus were the molecular ions of authentic HVA and HVA-d₂ respectively. The experimental error was less than 4%. The recovery of small amounts of authentic HVA added to CSF was satisfactory. Multiple ion determination using two sets of fragments gave similar results demonstrating high specificity and reproducibility of the method used.The mass spectral characteristics of the methyl ester heptafluorobutyryl derivative of ISO-HVA suggested that this compound could be differentiated from HVA by mass fragmentography. Thus the base peak did not constitute the molecular ion in the spectrum of the ISO-HVA-derivative as it is for the derivative of HVA. Multiple ion analysis of CSF before and after the addition of ISO-HVA failed to supply positive evidence for the presence of ISO-HVA in CSF in neurological or schizophrenic patients.