In the present study, the determination of histidine (HIS) by an on-line flow method based on the concept of zone fluidics is reported. HIS reacts fast with o-phthalaldehyde at a mildly basic medium (pH 7.5) and in the absence of additional nucleophilic compounds to yield a highly fluorescent derivative (λex/λem = 360/440 nm). The flow procedure was optimized and validated, paying special attention to its selectivity and sensitivity. The LOD was 31 nmol·L−1, while the within-day and day-to-day precisions were better than 1.0% and 5.0%, respectively (n = 6). Random urine samples from adult volunteers (n = 7) were successfully analyzed without matrix effect (<1%). Endogenous HIS content ranged between 116 and 1527 μmol·L−1 with percentage recoveries in the range of 87.6%–95.4%.

中文翻译：

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基于区域流体学的随机人尿液中组氨酸的荧光测定法

在本研究中，报道了基于区域流体学概念的在线流动法测定组氨酸 (HIS)。HIS 在弱碱性介质 (pH 7.5) 和没有其他亲核化合物的情况下与邻苯二甲醛快速反应，产生高荧光衍生物 (λex/λem = 360/440 nm)。流动程序经过优化和验证，特别注意其选择性和灵敏度。LOD 为 31 nmol·L-1，而日内和日间精度分别优于 1.0% 和 5.0%（n = 6）。来自成年志愿者 (n = 7) 的随机尿液样本在没有基质效应 (<1%) 的情况下成功进行了分析。内源性 HIS 含量范围为 116 至 1527 μmol·L-1，回收率范围为 87.6% 至 95.4%。