国标中铝的测定方法改进研究

Improvement of Aluminum Content Determination Method in Chinese National Standards

针对GB／T5009．182—2003《面制食品中铝的测定方法》中，铝的测定常因高氯酸残留而导致铬天青S显色不均，从而影响检测结果。文章通过实验研究、探索改进方法，旨在提高检测结果的准确性。方法：对铬天青显色剂的稳定性进行研究，以确定最佳显色时间；采用干法和湿法两种消解方法处理样品，通过氨水和盐酸调节pH值，以对硝基酚作为指示剂，使测定液酸度一致；比较干法和湿法两种方法的测定结果的准确度和精密度。结果：铬天青显色剂放置20min左右反应完全且稳定，线性较好，R^2=0．9974；干灰化法相对标准偏差（RSD）为3．3％，回收率为94．8％～103．2％；湿法相对标准偏差（RSD）为4．1％，回收率为92．7％-97．6％。两种方法检测结果无显著性差异（P〉0．05）。结论：改进后的方法与GB／T5009．182—2003相比具有显色均匀，结果准确，精密度高，更易于操作等优点，可作为食品中铝的测定参考方法。

Objective： When we determine the aluminum content in flour food with the method described in GB/TS009. 182 -2003, the Determination Method of Aluminum Content in Flour Food, the result is often inaccurate for the unevenly developed color of Chrome Azurol S caused by the residual of perchloric acid. The authors will find a renewed method to solve the problem. Methods ： To study the color development stability of Chrome Azurol S reagent so as to determine its best chromogenic time; the samples＇ was treated with dry digestion process and wet digestion process, the pH value was regulated with ammonia and hydrochloric acid, paranitrophenol was used as the indicator, so as to obtain the constant acidity of the test liquid＇; the accuracy and precision of the results obtained with the above two methods were compared. Results： Color development reagent of Chrom Azurol S was completely reacted and stable after about 20 minutes of placement, with good linearity of R^2 = 0. 9974 ; the RSD of dry digestion process was 3.3%, the recovery was 94.8% - 103.2% ;the RSD of wet digestion process was 4.1% ,the recovery was 92.7% - 97.6%. There was no Significant difference between the results obtained by two methods. Conclusion： Compared with the method described in GB/T5009. 182 -2003, the improved method has advantages of even color, accurate result, high precision and easy operation, which can used as a reference to determinate aluminum in food.