Elemental analysis of nuts and seeds by axially viewed ICP OES

A method for the multi-elemental determination of metals (Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Sr and Zn), metalloids (B and Si), and non-metals (Cl, P and S) in the babassu nut and mesocarp, sapucaia nut, coconut pulp, cupuassu pulp and seed, and cashew nut by axially viewed inductively coupled plasma optical emission spectrometry is presented. A diluted oxidant mixture (2 ml HNO3 + 1 ml H2O2 + 3 ml H2O) was used to achieve the complete decomposition of the organic matrix in a closed-vessel microwave oven. The accuracy of the entire proposed method was confirmed by standard reference material analysis (peach leaves-NIST SRM1547). The certified values showed a good agreement at a 95% confidence limit (Student’s t-test). The average RSD for repeatability of calibration solutions measurements were in the range of 1.1–6.7%. Limits of quantification (LOQ = 10 × LOD) were in the level of 0.00072–0.0532 mg/l. The macro and micronutrient ranges in the different nuts and seeds did not exceed the dietary reference intake (DRI), except for Mn in the babassu nut.