微波消解-电感耦合等离子体质谱法测定油条中的铝

Determination of aluminum in fried bread stick by microwave digestion-inductively coupled plasma-mass spectrometry

目的建立油条中铝含量的电感耦合等离子体质谱检测方法(ICP-MS)。方法用5 ml硝酸和2 ml过氧化氢为消解溶剂对样品进行微波消解,消解液蒸缩至1 ml左右,用纯水定容至50 ml,电感耦合等离子体质谱法进行定量检测。方法考察了酸度对响应值的影响,用1.0 ng/ml混合调谐液优化仪器工作条件,选用钪作为内标元素校正基体干扰和漂移。结果铝的质量浓度为0 mg/L^5.0 mg/L时,线性关系良好,线性回归方程为y=5 530x+62 184,相关系数(r)为0.999 3。方法的检出限为0.1μg/L。添加3种浓度水平的铝标准溶液测定方法的回收率,平均回收率为92.0%~102.0%,相对标准偏差为0.7%~3.2%。并应用该方法对油条样品中铝的含量进行了测定,发现15份样品中铝含量全部超标,含量为375 mg/kg^926 mg/kg。结论该方法灵敏度高、准确度好、检出限低、线性范围宽,适用于油条等面制食品中铝的测定。

Objective To develop a method for the determination of aluminum in fried bread stick by microwave digestion- inductively coupled plasma- mass spectrometry（ ICP- MS）. Methods The samples was conducted for microwave digestion with5 ml of nitris acid and 2 ml of hydroge peroxide. The digestion solution was evaporated to 1 ml and diluted to 50 ml with pure water,which was determined by ICP- MS. Effect of acidity was tested to response value and condition of instrument operation was optimized with 1. 0 ng/ml of mixed tune solution. Scandium was chosen as the internal standard,which was used to correct matrix interference and signal drifting. Results When aluminum concentration was within 0. 0 mg/L- 5. 0 mg/L,the linear relationship was good,and the linear regression equation was y = 5 530 x ＋ 62 184,with correlation coefficient（ r） = 0. 999 3.Detection limit of the method was 0. 1 μg/L. Recovery of the method was tested by addition of aluminum standard solution at 3concentration levels. The average recovery and the relative standard derivations of the method were within 92. 0%- 102. 0%and 0. 7%- 3. 2%. The developed method was applied to determine aluminum content in fried bread stick,with the concentration of aluminum in all 15 samples exceeding the standards within 375 mg/kg- 926 mg/kg. Conclusion The method shows high sensitivity,good accuracy,low detection limit,wide linear range,and is suitable for the determination of aluminum in wheaten food such as fried bread stick.