Heavy Metal Determination by Inductively Coupled Plasma - Mass Spectrometry (ICP-MS) and Direct Mercury Analysis (DMA) and Arsenic Mapping by Femtosecond (fs) - Laser Ablation (LA) ICP-MS in Cereals

A study of the lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) contents in popular cereals was conducted using inductively coupled plasma - mass spectrometry (ICP-MS), direct mercury analysis (DMA), and femtosecond laser ablation - inductively coupled plasma - mass spectrometry (fs-LA-ICP-MS). For Pb, Cd, and As determination, the samples were prepared using microwave digestion, while for Hg, the samples were homogenized and measured by DMA without additional pretreatment. Satisfactory values for all of the quality parameters that include the SD, limit of detection (LOD), limit of quantitation (LOQ), accuracy, and recovery were obtained, clearly validating the analytical techniques used in the current study. Recovery and accuracy measurements were done using rice flour CRM 108-01-002 from Korea Research Institute of Standards and Science (KRISS). All measured concentrations for these elements were lower than the national regulatory guideline values provided by the CODEX Alimentarius and Ministry of Food and Drug Safety. A sample from each group was also selected for an As distribution study within a grain using fs-LA-ICP-MS. As is classified as a first-class carcinogen by the International Agency for Research on Cancer (IARC). For adlay, oats, and barley, As was determined to be primarily distributed in the area where the grain splits, while for foxtail millet, sorghum and corn, As was concentrated in the grain embryo. Also, it was confirmed that the exposure of heavy metals in the diet was negligible due to the low metal concentrations consumed daily in these foods.