High‐Throughput Microwave‐Assisted Digestion and Extraction Procedures for Agricultural Materials

Despite the advances in microwave‐assisted procedures, the sample throughput still remains a critical problem that requires the development of reactor vessels, rotors, and procedures able to deal with a large number of samples simultaneously. In this work, a 36‐vessel rotor was combined with diluted nitric acid solution for digestion of agricultural materials. Accurate results were obtained for aluminum (Al), calcium (Ca), copper (Cu), iron (Fe), potassium (K), magnesium (Mg), manganese (Mn), phosphorus (P), and zinc (Zn) in bovine liver and spinach leaves standard reference materials. The EPA‐3051 method was also evaluated using this system. The procedure led to quantitative recoveries of chromium (Cr), Cu, Mn, nickel (Ni), and Zn in soil. All measurements were carried out using inductively coupled plasma—optical emission spectrometry (ICP‐OES). The main advantages of the proposed procedures are the increase of sample throughput in microwave‐assisted digestions or extractions and the lower dilution required before pneumatic nebulization of digests obtained by using dilute nitric acid.