Analytical Sciences

Determination of Minor and Trace Metals in Aluminum and Aluminum Alloys by ICP-AES; Evaluation of the Uncertainty and Limit of Quantitation from Interlaboratory Testing

Michihisa UEMOTO,*1 Masanori MAKINO,*2 Yuji OTA,*3 Hiromi SAKAGUCHI,*4 Yukari SHIMIZU,*5 and Kazuhiro SATO*6

*1 School of Science and Engineering, Meisei University, 2-1-1 Hodokubo, Hino, Tokyo 191-8506, Japan
*2 Kobelco Research Institute, Inc., Araicho, Takasago, Hyogo 676-8670, Japan
*3 Nippon Light Metal Co., Ltd., Kanbara, Shimizu, Shizuoka 421-3203, Japan
*4 Showa Denko K.K., Inuzuka, Oyama, Tochigi 323-8678, Japan
*5 UACJ Corp., Chitose, Minato, Nagoya, Aichi 455-8670, Japan
*6 Mitsubishi Aluminum Co., Ltd., Hiramatasu, Susono, Shizuoka 410-1127, Japan

Minor and trace metals in aluminum and aluminum alloys have been determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) as an interlaboratory testing toward standardization. The trueness of the measured data was successfully investigated to improve the analytical protocols, using certified reference materials of aluminum. Their precision could also be evaluated, feasible to estimate the uncertainties separately. The accuracy (trueness and precision) of the data were finally in good agreement with the certified values and assigned uncertainties. Repeated measurements of aluminum solutions with different concentrations of the analytes revealed the relative standard deviations of the measurements with concentrations, thus enabling their limits of quantitation. They differed separately and also showed slightly higher values with an aluminum matrix than those without one. In addition, the upper limit of the detectable concentration of silicon with simple acid digestion was estimated to be 0.03 % in the mass fraction.

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