高效液相色谱-电喷雾串联质谱法测定奶及奶制品中双氰胺和三聚氰胺

High performance liquid chromatography coupled with electrospray tandem mass spectrometry for the analysis of dicyandiamide and melamine residues in milk and milk products

目的建立高效液相色谱-电喷雾串联质谱法同时测定奶及奶制品中双氰胺和三聚氰胺的确证方法。方法样品经2．5％（Ⅳy）甲酸水溶液提取后，用乙腈沉淀蛋白，经微孔滤膜净化，Acquity UPLC BEH Amide色谱柱（100mm×2．1mm×1．7mm）分离，含0．1％（V/V）的乙腈-为流动相，梯度洗脱，采用串联四极杆质谱、电喷雾电离源正离子多反应监测模式检测，外标法定量。结果双氰胺和三聚氰胺浓度在5．0～1000．0μg／L时，线性关系良好（r分别为0．9995和0．9997），双氰胺和三聚氰胺的检出限均为10．0Ixg／kg；在0．050、1．0和10．0mg／kg3个添加水平范围内的平均回收率分别为86．0％～100．0％、90．0％～104．0％和90．0％-100．1％，相对标准偏差在1．06％～7．77％之间；加标样品日内重复测定的RSD分别为2．35％（双氰胺）和3．44％（三聚氰胺），日间重复测定的RSD分别为3．87％（双氰胺）和5．39％（三聚氰胺）。结论该法快速、准确、灵敏，优于传统的HPLC分析方法，适合于生产过程监控和日常检测的高灵敏度确证分析。

Objective To establish a sensitive method for the analysis of dicyanodiamide and melamine residue in milk and milk products by hydrophilic interaction liquid chromatography coupled with electrospray tandem mass spectrometry. Methods Samples were extracted with 2.5% （V/V） formic acid solution. Acetonitrile was used to precipitate proteins. The separation was carried on Acquity UPLC BEH Amide column （ 100 mm × 2. 1 mm × 1.7 mm） by gradient elution with acetonitrile - water as mobile phase. Identification was achieved by electrospray ionization （ESI） in positive mode using multiple reaction monitoring, and quantified with external standards. Results The dicyanodiamide and melamine were linear in the range of 5.0 -1000.0 μ.g/L with correlation coefficient of 0. 9995 for dicyanodiamide and O. 9997 for melamine. The detection limit of the method were 10.0 μg/kg for dicyanodiamide and melamine. The spiked at three levels ranged 86.0% - 100.0% （0. 050 mg/kg） , 90.0% - 104.0% （ 1.0 mg/kg）and 90.0% - 100. 1% （ 10.0 mg/kg）. And the relative standard derivations were lower than 1.06% -7. 77%. The within-day precisions were 2. 35% （dicyanodiamide）and 3. 44% （ melamine ）, and the inter-day precision 3. 87% （ dicyanodiamide ） and 5.39% （melamine）. Conclusion The method was sensitive, accurate and precise. It can be used in monitoring quality of milk production and daily analysis of milk and milk products.