Manganese (Mn) has been intentionally added to steel samples to promote their strength and toughness since the 19th century. Mn limits the internal porosity of the steel and provides the stability of the steel. Traditionally, the analysis of Mn in stainless steel was carried out using atomic absorption spectroscopy and UV/Vis spectrophotometry. However, the instrumentation for atomic absorption and UV/Vis analysis is bulky and inconvenient to use when a quick on-site analysis is needed. With the technology progress in portable electronic devices, a smartphone-assisted colorimetric method is developed to determine the amount of manganese in unknown samples. Stainless steel samples were first dissolved in the mixture of nitric acid and phosphoric acid to convert Mn into Mn2+. Aqueous Mn2+ was then oxidized by periodate to form permanganate (MnO4-), indicated by the characteristic purple color in aqueous solution. The intensity of different colors was measured by using Android phone with “Color Grab” application. By comparing the signal with the calibration curve of standard MnO4-, it was determined that 0.73%, 0.94%, and 0.54% of Mn were present in three different stainless steel samples, which agrees with the results obtained by the UV analysis and the true value. This project is supported by the Department of Chemistry and Biochemistry at California State Polytechnic University, Pomona.

Smartphone-assisted colorimetric analysis of Mn in stainless steel

253rd National Meeting (2017)

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