de Jong A P, Kok R M, Cramers C A, Wadman S K, Haan E
Department of Pediatrics, Free University Hospital, Amsterdam, The Netherlands.
Clin Chim Acta. 1988 Jan 15;171(1):49-61. doi: 10.1016/0009-8981(88)90290-2.
L-3-(3,4-Dihydroxyphenyl)alanine (DOPA) and its 3-O-methyl metabolite (OMD) were measured in plasma and cerebrospinal fluid by a new assay which combines N,O-acetylation of amino acids in aqueous media, preparation of pentafluorobenzyl esters under anhydrous conditions, and analysis by gas chromatography-electron capture negative ion mass spectrometry. The N,O-acetyl, carboxy-PFB derivatives gave abundant carboxylate anions ([M-CH2C6F5]-) which were suitable for sensitive analysis using selected ion monitoring. Plasma and CSF samples were sufficiently purified by a simple organic solvent extraction. Analytical recovery for DOPA was 100.2 +/- 3.7% at the level of 100 nmol/l. Analysis of DOPA in plasma was performed with a relative standard deviation of 5%. The limit of quantitation in plasma and CSF was at the sub-nmol/l level. In healthy adults, DOPA concentration in plasma was 9.0 +/- 2 nmol/l (n = 11) and in CSF 3.5 +/- 0.9 nmol/l (n = 9). The concentration of OMD in plasma was 99.1 nmol/l (pool of 24 samples) and 15.3 nmol/l in CSF (pool of 12 samples). Measurement of 5-[2H]DOPA and 5-[2H]OMD in plasma of a healthy individual who had been orally loaded with 3,5-[2H2]tyrosine (150 mg kg body wt) was possible for several hours after the load.
采用一种新的检测方法，通过在水介质中对氨基酸进行N，O - 乙酰化、在无水条件下制备五氟苄酯以及利用气相色谱 - 电子捕获负离子质谱进行分析，来测定血浆和脑脊液中的L - 3 -（3,4 - 二羟基苯基）丙氨酸（多巴）及其3 - O - 甲基代谢物（OMD）。N，O - 乙酰、羧基 - PFB衍生物产生丰富的羧酸根阴离子（[M - CH2C6F5]-），适用于采用选择离子监测进行灵敏分析。血浆和脑脊液样品通过简单的有机溶剂萃取得到充分纯化。在100 nmol/l水平下，多巴的分析回收率为100.2±3.7%。血浆中多巴的分析相对标准偏差为5%。血浆和脑脊液中的定量限在亚nmol/l水平。在健康成年人中，血浆中多巴浓度为9.0±2 nmol/l（n = 11），脑脊液中为3.5±0.9 nmol/l（n = 9）。血浆中OMD浓度为99.1 nmol/l（24个样品的混合液），脑脊液中为15.3 nmol/l（12个样品的混合液）。在口服3,5 - [2H2]酪氨酸（150 mg/kg体重）的健康个体血浆中，负荷后数小时内能够测定5 - [2H]多巴和5 - [2H]OMD。
