Quantification of selenated amino-acids currently relies on methods employing inductively coupled plasma mass spectrometry (ICP-MS). Although very accurate, these methods do not allow the simultaneous determination of standard amino-acids, hampering the comparison of the content of selenated versus non-selenated species such as methionine (Met) and selenomethionine (SeMet). This paper reports two approaches for the simultaneous quantification of Met and SeMet. In the first approach, standard enzymatic hydrolysis employing Protease XIV was applied for the preparation of samples. The second approach utilized methanesulfonic acid (MA) for the hydrolysis of samples, either in a reflux system or in a microwave oven, followed by derivatization with diethyl ethoxymethylenemalonate. The prepared samples were then analyzed by multiple reaction monitoring high performance liquid chromatography tandem mass spectrometry (MRM-HPLC-MS/MS). Both approaches provided platforms for the accurate determination of selenium/sulfur substitution rate in Met. Moreover the second approach also provided accurate simultaneous quantification of Met and SeMet with a low limit of detection, low limit of quantification and wide linearity range, comparable to the commonly used gas chromatography mass spectrometry (GC–MS) method or ICP-MS. The novel method was validated using certified reference material in conjunction with the GC-MS reference method.

目前，硒化氨基酸的定量依赖于采用电感耦合等离子体质谱法（ICP-MS）的方法。尽管非常准确，但这些方法无法同时测定标准氨基酸，这妨碍了对硒化和非硒化物种（如蛋氨酸（Met）和硒代蛋氨酸（SeMet））含量的比较。本文报告了同时定量Met和SeMet的两种方法。在第一种方法中，将采用蛋白酶XIV的标准酶水解方法用于样品制备。第二种方法是使用甲磺酸（MA）在回流系统或微波炉中水解样品，然后用乙氧基亚甲基丙二酸二乙酯衍生化。然后通过多反应监测高效液相色谱串联质谱法（MRM-HPLC-MS / MS）分析制备的样品。两种方法均提供了准确测定大都会中硒/硫取代率的平台。此外，第二种方法还提供了Met和SeMet的精确同时定量，其检测限低，定量限低和线性范围宽，可与常用的气相色谱质谱法（GC-MS）或ICP-MS相媲美。该新方法已通过认证的参考材料和GC-MS参考方法的验证。此外，第二种方法还提供了Met和SeMet的精确同时定量，其检测限低，定量限低和线性范围宽，可与常用的气相色谱质谱法（GC-MS）或ICP-MS相媲美。该新方法已通过认证的参考材料和GC-MS参考方法的验证。此外，第二种方法还提供了Met和SeMet的精确同时定量，其检测限低，定量限低和线性范围宽，可与常用的气相色谱质谱法（GC-MS）或ICP-MS相媲美。该新方法已通过认证的参考材料和GC-MS参考方法的验证。