Determination of macro, essential trace elements, toxic heavy metal concentrations, crude oil extracts and ash composition from Saudi Arabian fruits and vegetables having medicinal values

Abstract

The concentrations of essential elements (Mg, Ca, Na, K, Fe, Zn, Se, Al, Ni, and Cu) and toxic heavy metals (Pb, As, Cr, Cd, and Cr) from Saudi Arabian fruits and vegetables were determined by inductively coupled plasma optical emission spectrophotometry (ICP/OES). Two types of butters, Caralluma munbayana and Caralluma hesperidum, Vigna (Vigna unguiculata), common fig (Ficus carica), Annona seeds (Annonaceae seeds), Annona fruits (Annonaceae fruits), Fennel (Foeniculum vulgare), and Fennel flowers (Nigella sativa) were investigated, because they are used by indigenous groups as traditional medicines with Soxhlet-extraction and dry-ashing protocol. The estimated daily dietary element intake in food samples was further calculated in order to evaluate the element dietary intake and fruit and vegetable consumption pattern of the indigenes of Saudi Arabia. The crude oil and ash compositions varied widely, but suggested that most of the foods were good sources of oils and minerals. The figures-of-merit of the ICP-OES calibration curves were excellent with good linearity (R2 > 0.9921). The use of ICP-OES in this study allowed the accurate analysis and the detection of the elements at low levels. Essential elements (K, Ca, Na, and Mg) had the highest concentrations while toxic heavy metals (As, Pb, and Cd) had the lowest in the foods. Essential element pairs (Mg-Na, Mg-Ca, Fe-Al) were highly correlated, suggesting that these foods are sources of multiple nutrients. Toxic element pairs (Pb-Cd, Pb-As, and Cd-As), however, were poorly correlated in the foods, suggesting that these elements do not have a common source in these foods. Average consumption of these foods should provide the recommended daily allowances of essential elements, but will not expose consumers to toxic heavy metals. The ICP-OES method was validated by determining method detection limits and percent recoveries of laboratory-fortified blanks, which were generally 90–100%.

Keywords

• Chemical-elements-analysis
• Food-quality-assurance
• Inductively-coupled-plasma-emission-spectroscopy
• Inter-element-association
• Daily-dietary intake-estimate
• Saudi-Arabian-foods