Heavy metal toxins in breakfast cereals – a baseline study using hybrid plasma mass spectrometry

Abstract

Plasma mass spectrometry is renowned for its high performance and impeccable capability and is a valuable asset for ultra-trace analysis of heavy metals. Heavy metal contamination of foodstuff is hazardous to human health and necessitates stringent analytical procedures to accurately evaluate toxic levels in samples. Our research team undertook investigation of the levels of arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) in eight brands of breakfast cereals as an initiative to provide guidelines for such elements in cereals. Inductively coupled plasma mass spectrometry (ICP-MS) was employed to detect concentrations of the toxins under study. The technique is one of the foremost in trace analysis and the capability of the instrument was validated by the use of certified reference standards. Minor aberrations in performance were monitored by the use of internal standards. Linearity, background correction and the removal of interferences were attained by deployment of sophisticated software. The argon flow associated with the plasma torch was 14.0L/min. Cereal samples were digested in ultrapure nitric acid, diluted in mild aqueous media (1% HNO3) and subjected to ICP-MS analysis. The elements under study produced appreciable levels in most samples: Arsenic: 100-900μg/L; cadmium: 8-50μg/L; mercury: 270-370μg/L; lead: 115-30000μg/L. These values were compared with EU permissible levels in general foodstuffs and were found to be within the acceptable limit, except for Pb, which displayed elevated levels up to a factor of 5 in some samples. Our study makes a definite contribution to sustainable living and would be of interest to food safety organizations.