Indirect Spectrophotometric Method Based on a Selective Reaction Between Bicinchoninic Acid and Copper(I) for the Determination of Metal Ions.

The development of facile, sensitive, and robust methods for the detection of metal ions is fascinating for chemists because traditional strategies for their detection usually involve complicated instrumentation and critical sample preparation procedures. In this work, bicinchoninic acid was used in a specific reaction with Cu(I) for the spectrophotometric determination of various metal ions. The optimization of experimental parameters led to the establishment of a simple, fast, and accurate analytical method. Mn(II), Co(II), and Fe(II) can be detected at submicromolar levels using this method. Calibration graphs for Mn(II), Co(II), and Fe(II) are rectilinear within the range of 8–40, 15–150, and 15–150 μM, respectively. The detection limit for Mn(II), Co(II), and Fe(II) were 0.83, 1.4, and 1.9 mg/L, respectively, and the relative standard deviation did not exceed 2.5% for five replicates. The bathocuproine reaction demonstrated that Cu(II) can be reduced to Cu(I) by Mn(II). Then bicinchoninic acid can bind to Cu(I), creating a purple-colored product at 562 nm. The method has been successfully applied to evaluate the reaction process and stability of metal-organic frameworks. Moreover, the results were found to be in satisfactory agreement with those acquired by using the inductively coupled plasma mass spectrometry technique, which will open up a new avenue for using the proposed strategy as a conventional method to detect metal ions in scientific research. [ABSTRACT FROM AUTHOR]