Cultivation of Goji Berries (Lycium Barbarum and Lycium Ruthenicum) in the Maltese Islands: An Analysis of the Main Nutrients and Vitamins Found in Fresh Berries
5.2.1 Determination of Metal Content
The procedures used by Niro et al. (2017) differed from the experiment conducted in this project because they used 96% sulphuric acid during the mineralisation phase. Consequently, analysis of these inorganic minerals was done through spectrophotometry plasma emission (Varian ICP 710, OES Inductively Coupled PlasmaOptical Emission Spectrometers, Palo Alto, CA 94304-1038). Here, Niro et al. (2017) used a similar method as the project including plasma atomic emission spectroscopy, though the researchers used different equipment to carry out the procedure. While Niro et al. (2017) used Inductively Coupled PlasmaOptical Emission Spectrometers, the current project used MP-AES to carry out the same procedure. Michalke & Nischwitz (2017) explain that atomic emission spectrometry involves atomisation and ionisation of elemental species in high-temperature plasma. In the experiment by Niro et al. (2017), 0.5g of ground goji samples was mixed with 10ml of nitric acid and mineralizer recommended by SCP Science DIGIprep, Quebec H9X 4B6, Canada. The conditions for the experiment were modified as illustrated below. The temperature was set at 400 for 15 minutes, then heated at 600C for 15 minutes, temperature maintained at 600C for 15 minutes, followed by heating at 900C for 20 minutes. This procedure is a bit different from the protocols used in this project because, here heating was done at temperatures reaching 500⁰C when changing the samples into ash after digestion with nitric acid.