Cadmium preconcentration with bean-coat as a green adsorbent with detection by electrothermal atomic absorption spectrometry

Abstract

A novel green/biodegradable adsorbent, mungbean-coat, has been investigated for the adsorption of ultra-trace amounts of cadmium. Carboxylic groups on the bean-coat effectively retain the cadmium ions via coordinative interactions. This well facilitates the adsorption of cadmium ions which can readily be recovered by acid elution. In practice, bean-coat is used to pack a mini-column for on-line adsorption and preconcentration of cadmium from environmental samples with detection by electrothermal atomic absorption spectrometry. By using a sample loading volume of 1.4 mL and an eluent volume of 70 μL, an enrichment factor of 19.8 along with a detection limit of 1.4 ng L⁻¹ are achieved. A precision of 2.4% RSD at the level of 0.05 μg L⁻¹ is derived. The present procedure has been applied for the determination of cadmium in certified reference materials (GBW08608 Trace Elements in Water and CRM 176 Trace Elements in a City Waste Incineration Ash) and a snow water sample. Fair agreements are reached between the certified values and the experimental results, in addition to a satisfactory spiking recovery for the snow water sample. In the present work, the use of green and biodegradable adsorbent as well as the elimination of use of organic solvent/eluent facilitates the development of a green analytical protocol.