Abstract

Tryptophan is essential amino acid and precursor for many neurotramsmiters that must be obtained from dietary proteins. However, its free form is easily absorbed and could increase the availability of this amino acid to the brain. Because of free tryptophan interaction with human health simple, eco-friendliness and low-cost method of determination are still needed. In this study, new and simple procedure for free tryptophan determination using capillary isotachophoresis is discussed. The method validation pointed good linearity, satisfactory selectivity, accuracy (recoveries varied from 98.4 to 100.1%), intra- and inter-day precision (coefficent of variation was < 5% for each standard solution and < 6% for real samples) and no matrix effect. The proposed procedure was successfully applied to analyse free tryptophan in beer samples and found contents varied from not detected to 40.74 ± 0.27 mg L⁻¹. The obtained results were compared with chromatographic determination after derivatization with 2-chloro-1,3-dinitro-5-(trifluoromethyl)benzene and pointed better selectivity and accuracy of isotachophoretic procedure with similar precision. Due to the simplicity and flexibility, the proposed procedure is suitable for tryptophan analysis in complex matrices.

中文翻译：

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毛细管等速电泳法测定啤酒样品中的游离色氨酸

摘要

色氨酸是必需的氨基酸，是许多必须从饮食蛋白中获得的神经传递蛋白的前体。但是，它的游离形式很容易被吸收，并且可以增加这种氨基酸对大脑的利用率。由于色氨酸与人体健康的简单相互作用，因此仍然需要生态友好和低成本的测定方法。在这项研究中，讨论了使用毛细管等速电泳测定游离色氨酸的新的简单方法。方法验证表明良好的线性，令人满意的选择性，准确性（回收率从98.4％到100.1％），日内和日间精度（每个标准溶液的变异系数<5％，真实样品的变异系数<6％），并且没有矩阵效应。未检测到40.74±0.27 mg L ^-1。将所得结果与2-氯-1,3-二硝基-5-（三氟甲基）苯衍生化后的色谱测定结果进行比较，结果表明，等速电泳程序具有更好的选择性和准确性，且精度相似。由于其简单性和灵活性，所提出的程序适用于复杂基质中的色氨酸分析。