Hydrolyzed leather proteins have been used illegally by some dairy industries in dairy products to increase the protein content in the last few years. As a specific amino acid in collagen, the detection of L-hydroxyproline (L-Hyp) can be used to indicate whether the hydrolyzed leather proteins are added to dairy products or not. A sensitive capillary electrophoretic method with in-capillary optical fiber light-emitting diode-induced fluorescence detection (ICOF-LED-IFD-CE) was developed for the determination of L-Hyp and further for identification of hydrolyzed leather proteins in dairy products. Fluorescein isothiocyanate (FITC) labelled L-Hyp (FITC-Hyp) was detected in a background electrolyte of 20 mM sodium borate at pH 9.4 and an applied voltage of 17 kV in less than 8 min. The limit of detection (LOD) for FITC-Hyp was 0.61 nM at the signal to noise ratio (S/N) of 3. The intraday precision (n = 6) of migration time and peak area was 2.65% and 1.97%, while the interday precision (n = 6) of migration time and peak area was 1.54% and 2.36%, respectively. The accuracy of the proposed method was judged by standard addition method, spectrophotometry method and commercial LIF-CE, and the results indicated that the proposed method was reliable. The ICOF-LED-IFD-CE method was successfully applied to determine L-Hyp in dairy products.

中文翻译：

---

毛细管电泳-毛细管内光纤发光二极管诱导的荧光检测 灵敏测定乳制品中的l-羟脯氨酸

在过去的几年中，某些乳制品行业已将水解皮革蛋白非法用于乳制品中，以增加蛋白质含量。作为胶原蛋白中的特定氨基酸，L-羟脯氨酸（L -Hyp）的检测可用于指示是否将水解的皮革蛋白添加到乳制品中。开发了一种利用毛细管内光纤发光二极管诱导的荧光检测（ICOF-LED-IFD-CE）的灵敏毛细管电泳方法，用于测定L -Hyp并进一步鉴定乳制品中的水解皮革蛋白。异硫氰酸荧光素（FITC）标记为L在不到8分钟的时间内，在pH值为9.4的20 mM硼酸钠背景电解液和17 kV的施加电压中检测到-Hyp（FITC-Hyp）。信噪比（S / N）为3时，FITC-Hyp的检出限（LOD）为0.61 nM 。迁移时间和峰面积的日内精度（n = 6）为2.65％和1.97％，而迁移时间和峰面积的日间精度（n = 6）分别为1.54％和2.36％。通过标准加入法，分光光度法和商用LIF-CE对所提方法的准确性进行了判断，结果表明所提方法是可靠的。ICOF-LED-IFD-CE方法已成功应用于乳制品中L -Hyp的测定。