Multielemental analysis in small amounts of environmental reference materials with inductively coupled plasma mass spectrometry

The lowest possible sample weight for performing multielemental trace element analysis on environmental and biological samples by ICP-MS has been investigated. The certified reference materials Bovine Liver NIST SRM 1577b, Human Hair NCS DC 73347 and Oriental Tobacco Leaves CTA-OTL-1 were applied at sample weights (1, 5, 20 and 50 mg aliquots, n = 10) which were significantly lower than those recommended with most recoveries in the range of 95-110%. Samples were digested in a mixture of nitric acid, hydrogen peroxide and hydrogen fluoride by closed-vessel microwave digestion. Multielemental analysis was performed with an optimized ICP-QMS method. Aqueous standard solutions were applied for external calibration with rhodium as the internal standard element. The detection limits varied between 0.02-0.38 mu g/g for Li, Na, Cr, Mn, Ni, Cu, Zn, Sr, Cd, Ba and Pb, and up to 1.92 mu g/g for Mg, Al, Ca, Fe and Ni. Digested human plasma samples were spiked with multielemental solution (0.5-10 mu g/L) to test the analytical method and the recoveries were 95-105% for most analytes. Our results show that in the case of homogeneous SRMs it is possible to use them in very low amounts (1-5 mg) for method development and quality control.