Determination of trace cadmium and zinc in corn kernels and related soil samples by atomic absorption and chemical vapor generation atomic fluorescence after microwave-assisted digestion

Various hybrids or inbred lines of corn kernels and their corresponding soils were sampled from Sichuan, China, for the investigation of cadmium and zinc transfer from soil to corn. A new analytical procedure based on closed-vessel microwave-assisted digestion and chemical vapor generation atomic fluorescence spectrometry (CVG-AFS) was investigated for the determination of total trace cadmium in the corn samples, with accuracy confirmation by inductively coupled plasma atomic emission spectrometry (ICP-AES). Flame atomic absorption spectrometry (FAAS), also with accuracy confirmation by ICP-AES, was used for the determination of total Zn in the corn, also after the microwave digestion. For the corresponding soil samples, an incomplete digestion procedure (leaching or extraction) by 3 mL HNO3 and 3 mL H2O2 proved to be adequate for the determination of zinc by FAAS, whereas a complete decomposition of the samples by the combination of 4 mL HNO3 , 3 mL HF, and 2 mL H2O2 was needed for the determination of cadmium by ICP-AES. A linear correlation was found between zinc content in corn kernels and that in the corresponding soil samples.