高效液相色谱荧光检测法测定豆芽中尿素含量

摘要

A method of urea contents in soybean sprouts tested using high performance liquid chromatography fluorescence detection was developed. Samples were extracted using ethanol, derivatized with acidic xanthydrol solution and separated with RP C18 column, the mobile phases were acetonitrile and 0.02 mol/L sodium acetate solution, performed with gradient elution and determined with fluorescence detection atλex 213 nm andλem 308 nm. The results showed there was a good linear correlation for peak areas and urea contents in the range of 1.0 mg/L-50 mg/L;the r2 was greater than 0.999. The limit of detection (S/N=3) was 0.5 mg/kg.When spiked with 5, 25 and 50 mg/kg, the spiked recoveries were 98.5%-106%, respectively, RSD%was less than 4%. Urea contents of lab germinated soybean sprouts, green food labeled and bulk soybean sprouts purchased in market were in the range of 3.5-14.1 (n=6), 5.7-10.4 (n=4) and 7.6-148 (n=35) mg/kg, respectively. It is a simple accurate, sensitive and highly specific method with good reproducibility.%建立了高效液相色谱荧光检测法测定豆芽中尿素的方法。样品用乙醇提取，提取液在酸性条件下用呫吨氢醇衍生，衍生产物经Agilent Eclipse XDB-C18柱（150 mm ×4.6 mm，5μm）分离，乙腈和0.02 mol/L乙酸钠溶液为流动相，梯度洗脱，荧光检测器检测波长λex 213 nm和λem 308 nm。结果表明：尿素的质量浓度在1.0 mg/L～50 mg/L范围内，峰面积与质量浓度呈良好的线性关系，r2大于0.999，方法检出限为（S/N=3）0.5 mg/kg；尿素添加浓度为5、25、50 mg/kg时，加标回收率98.5%～106%，RSD%小于4%。采用该方法检测实验室自发豆芽、绿色食品标签豆芽和市售散装豆芽（绿豆芽和黄豆芽）尿素含量不等，浓度范围分别在3.5 mg/kg~14.1 mg/kg（n=6），5.7 mg/kg~10.4 mg/kg（n=4）和7.6 mg/kg~148 mg/kg （n=35）。该方法简便、准确、灵敏、专一性强、重现性好。