Determination of Trace Levels of Iron in Spinacia Oleracea Using Microcontroller-Based Photometer

Abstract

AbstractThis work aims to investigate the trace levels of iron in different species of spinach using spectrophotometric analysis and a low-cost, simple and portable photometer built with a microcontroller. Experimental results show that iron reacts with 1,10-phenanthroline to produce an orange-red complex, which has a maximum absorption at a wavelength of 511 nm. The linear calibration graphs were obtained for 2 × 10–4 to 4 × 10–3 mg/ml of iron (II), with a correlation coefficient of 0.9994 for the iron(II)-phenanthroline complex. The molar absorption coefficient was found to be 8.642 × 103 L mol−1 cm−1. The limit of detection is 1.1426 × 10–4 mg/ml. Nine different interference ions were investigated, and only copper and zinc, when added in excess, are found to interfere significantly with the absorbance of the complex. The iron(II)-phenanthroline complex is stable over 24 h. Under optimal conditions of temperature and pH, the concentration of iron in red and green spinach was successfully determined using our proposed method and achieved ±5% accuracy compared to a benchtop spectrophotometer which served as the reference.