Determination of Manganese in Whole Blood By Stripping Analysis with Indium Tin Oxide

Abstract

Manganese (Mn) is a required trace metal in the body. In recent years however, it has garnered significant attention as a developmental neurotoxin in children with chronic exposure. It has been linked to complications such as memory loss with negatively associated IQ scores, attention deficit hyperactivity disorder (ADHD), and in extreme cases, the development of a Parkinson’s disease analogue- manganism. For these reasons among others, the Environmental Protection Agency has set the maximum contaminant level (MCL) in drinking water at a very low concentration of 50 ppb (0.9 μM). Thus, trace detection of this neurotoxic metal in both environmental and biological samples has become very important. Cathodic stripping voltammetry has proven to be a suitable method for electroanalytical determination of Mn. We have established Mn CSV using indium tin oxide (ITO) as the working electrode for the determination of Mn in bovine whole blood after an acid digestion. Reliable, accurate, and precise results were obtained as only 9% variation in the digested blood was observed. The CSV results were compared with graphite-furnace atomic absorption spectroscopy (GF-AAS) and inductively coupled plasma- mass spectrometry (ICP-MS) and favorable agreement across the methods was observed. We also fabricated ITO on non-optically transparent substrates where we observed improved electrochemical response compared to that of commercially available ITO. This was completed by varying pre-treatments, fabrication processes, and post-processing of the ITO electrodes. Due to ITO’s excellent positive potential window and stability under harsh environments, this method could be applied to other oxide-forming transition metals detectable by CSV. Figure 1