抄録
Gas chromatography-mass spectrometry makes possible the simultaneous measurement of homovanillic acid (HVA), vanilmandelic acid (VMA) and 3, 4-dihydroxy mandelic acid (DOMA) in 2ml urine samples.
The equipment used was the Shimadzu LKB 9000 GC-MS (MID-PM). The TMSi derivatives of the compounds were analysed by the GC-MS system equipped with a 3ft × 3mm column packed with 1.5% OV-1 and the temperature was programed from 130° to 260°C at 10°C/min increments. The mass spectrum showed molecular ions at m/e 326,414 and 472 which correspond to the TMSi derivatives of HVA, VMA and DOMA respectively.
The peaks at m/e 326 (HVA), 297 (VMA) and 355 (DOMA) were applied to avail themselves of simultaneous multiple ion analyses by GC-MS.
As little as 1pg of the compounds injected into the column could be measured reproducibly. The sensitivity is of the order of pg or ng, and the linearity of the response is maintained up to at least 200ng.
The procedure was simpler and less time consuming than previous methods. It consists of extraction of the free acid into ether followed by complete silylation of the phenolic, alcoholic and carboxylic acid group with bis (trimethylsilyl) acetamide.
Recoveries of HVA, VMA and DOMA added to urine were 93.8%, 71.2% and 23.6% respectively. The specificity of this method surpasses and cannot be compared to any other existing quantitative methods.
