Food Safety and Environmental Stewardship Program

A simple automated micro-digestion and analysis method was developed for the determination of 17 elements (Na, K, Mg, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Cd, Pb, P, and S) in plant tissue samples (i.e., feed, forage, crops). A 0.25-1.0 g sample was digested with nitric acid in a 10-mL graduated Kimax culture tube on a programmed heating block. Each element was quantified by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The digestion and analysis method demonstrated statistical control of environmental and biological samples. In comparison to other commonly used methods the dilution was 10, which is an important consideration for low concentration elements that are near instrument detection limits. The method uses only modest sample sizes, needs infrequent supervision during digestion, requires no further extractions or quantitative trans fers, and is amenable to autosampling. The ICP-AES operational parameters have been optimized to allow for the quantification of the above elements in 10-mL plant samples. The small sample size minimizes reagents used and their subsequent waste disposal.