title: Microwave heated vapor-phase digestion method for biological sample materials.
abstract: A microwave heated, vapor-phase nitric acid-hydrogen peroxide digestion method for pulverized, biological sample materials was developed. Sample masses up to 200 mg were digested using calibrated quartz inserts inside first generation type, low-pressure, Teflon-PFA microwave vessels. In the first step, samples were digested in the vapor-phase for 80 min using a progressive heating pattern. Three mL of 70% nitric acid and 0.5 mL of 30% hydrogen peroxide were used as digestion reagents. In the second step, the small residue left after first step digestion was dissolved in 1.4% nitric acid or additionally with 0.5% hydrofluoric acid by heating for 15 min. The digestion method was optimized using pike (Esox lucius) muscle as a test material. The method was further optimized using three certified reference materials. Ca, Cu, Fe, Mg and Zn were determined from NIST-SRM 1577a bovine liver by ICP-AES. Cr and Ni were determined from NIST-SRM 8433 corn bran and NRCC DOLT-2 dogfish liver by GFAAS. For all elements the values obtained were close or within certified limits. Spike recoveries were between 96 to 107%. Digestion efficiency ranged from 91 to 99%.
authors.affiliation: University of Oulu, Department of Chemistry, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Eilola
authors.forename: P
authors.initials: P
authors.lastname: Perämäki
mesh_terms: D000818:Animals; D002417:Cattle; D004284:Dogfish; D017859:Esocidae; D006861:Hydrogen Peroxide / Q000737:chemistry; D007202:Indicators and Reagents; D008099:Liver / Q000737:chemistry; D008670:Metals / Q000032:analysis*; D008872:Microwaves; D009569:Nitric Oxide / Q000737:chemistry; D013054:Spectrophotometry, Atomic; D003313:Zea mays / Q000737:chemistry
chemical_list: D007202:Indicators and Reagents; D008670:Metals; D009569:Nitric Oxide; D006861:Hydrogen Peroxide