液相色谱-稳定同位素比值质谱测定燕窝中唾液酸的碳稳定同位素比值

Determination of carbon stable isotope ratios of sialic acid in bird’s nests by liquid chromatography-stable isotope ratio mass spectrometry

该文建立了适合液相色谱-稳定同位素比值质谱(liquid chromatography-stable isotope ratio mass spectrometry,LC-IRMS)测定干燕窝中唾液酸δ^(13)C值的方法。样品前处理方法加标回收率为75.2%~100.6%,前处理方法可显著降低蛋白质等大分子对色谱柱的影响且不会干扰碳稳定同位素的准确分析;研究并优化了LC-IRMS对唾液酸δ^(13)C值测定的影响,优化后的色谱条件:采用Hyper REZ XP Carbohydrate H+(300 mm×7.7 mm,8μm)柱,柱温30℃,在0.250 mL/min流速下用90%B(H_(2)O)+10%D(pH_(2)的H_(2)SO_(4))洗脱。方法稳定性、重复性均良好,可准确测定样品δ^(13)C值。对6个干燕窝样品和4个市售唾液酸进行测定,其唾液酸δ^(13)C值分别为(-29.55±0.39)‰和(-15.18±2.45)‰,2种不同来源唾液酸碳稳定同位素特征显著。可检测到燕窝中的非法掺入市售唾液酸比例最低为10%。该方法的建立可为后续鉴别燕窝制品外源添加唾液酸提供基础。

In this paper,a method was developed for the determination of sialic acidδ^(13)C values in dried bird’s nests by liquid chromatography-stable isotope ratio mass spectrometry(LC-IRMS).The recoveries of the sample off-line pretreatment method ranged from 75.2%to 100.6%,and the pretreatment process could significantly reduce the influence of large molecules such as proteins on the column without causing isotopic fractionation.The effect of LC-IRMS on the determination ofδ^(13)C values of sialic acid was investigated and optimized.A Hyper REZ XP Carbohydrate H+(300 mm×7.7 mm,8μm)column with a column temperature of 30°C was used,eluting with 90%B(H_(2)O)+10%D(pH_(2) H_(2)SO_(4))at a flow rate of 0.250 mL/min.The method was stable and reproducible for the accurate determination of theδ^(13)C value of sialic acid.Six dried bird’s nest samples and four commercial sialic acids were determined withδ^(13)C values of(-29.55±0.39)‰and(-15.18±2.45)‰,respectively,and the two different sources of sialic acids had obvious carbon stable isotope characteristics.The percentage of illegally adulterated commercial sialic acid in bird’s nests could be detected at 10%.This method can provide a basis for the subsequent identification of exogenously added sialic acid in bird’s nest products.