Gilbert R B, Peng P I, Wong D
Department of Pathology, Santa Clara Valley Medical Center, San Jose, CA 95128, USA.
J Anal Toxicol. 1995 Mar-Apr;19(2):84-6. doi: 10.1093/jat/19.2.84.
A metabolite of labetalol that is responsible for previous reports of false-positive assays for amphetamines by thin-layer chromatography and immunoassay has been identified. The compound, 3-amino-1-phenylbutane (APB), an oxidative metabolite of labetalol, was initially identified in a patient's urine by gas chromatography-mass spectrometry and confirmed by analysis of the pure material. Gas chromatography showed a single major peak with relative retention time indistinguishable from that of methamphetamine, both underivatized and as the pentafluoropropionyl derivative. By classical thin-layer chromatography, APB migrated identically to methamphetamine but showed ninhydrin color development characteristic of amphetamine. APB was shown to cross-react approximately 2% with the Abbott TDx amphetamine/methamphetamine II kit, 10% with the Syva EMIT d.a.u. polyclonal amphetamine class kit, and 3% with the Syva EMIT d.a.u. monoclonal amphetamine kit. This degree of cross-reactivity is sufficient to cause false-positive immunoassays when cutoffs of 300 ng/mL are used.
已鉴定出拉贝洛尔的一种代谢物，该代谢物是先前薄层色谱法和免疫分析法检测苯丙胺出现假阳性报告的原因。化合物3-氨基-1-苯基丁烷（APB）是拉贝洛尔的一种氧化代谢物，最初通过气相色谱-质谱法在一名患者的尿液中鉴定出来，并通过对纯物质的分析得到证实。气相色谱显示，在未衍生化以及作为五氟丙酰衍生物的情况下，均有一个主要峰，其相对保留时间与甲基苯丙胺无法区分。通过经典薄层色谱法，APB的迁移情况与甲基苯丙胺相同，但显示出苯丙胺特有的茚三酮显色。结果表明，APB与雅培TDx苯丙胺/甲基苯丙胺II试剂盒的交叉反应率约为2%，与西瓦EMIT d.a.u.多克隆苯丙胺类试剂盒的交叉反应率为10%，与西瓦EMIT d.a.u.单克隆苯丙胺试剂盒的交叉反应率为3%。当使用300 ng/mL的临界值时，这种交叉反应程度足以导致免疫分析出现假阳性。
