Determination of trace elements in Indian rice by ETAAS and ICP-AES

Essential (Fe, K, Cu, Zn, Mn) and toxic (Pb, Cr, Cd) trace metals in major Indian rice varieties were determined by electro thermal atomic absorption (ETAAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) techniques. A combined use of UV photolysis and hydrogen peroxide in the presence of an oxidant (HNO3) results in the complete destruction of the organic matrix in the rice samples. Commonly consumed rice varieties from different regions of India were digested using UV photolysis and the trace elements were determined by ETAAS and ICP-AES. The data show that, in general, the milled rice contains lower micronutrients (Fe, K, Zn) than the parboiled / brown rice. The Fe content in the rice varieties analyzed was found to be in the range of 0.32 to 4.2 mg/100 g. The two un-hybridized varieties (red, black) were found to contain a higher concentration of Fe at 3-4 mg/100 g. The aromatic rice (Basmati) and the unhybridized black rice contain higher amount of Zn. A standard reference material of rice flour (NIST SRM 1568a) was used for validating the analytical results.