Comparison of laser ablation and dried solution aerosol as sampling systems in inductively coupled plasma mass spectrometry

Influence of different metal matrices on manganese signal response in laser ablation inductively coupled plasma-mass spectrometry

Laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) is applied for the quantitative determination of manganese concentration in metal samples. A set of Certified Reference Materials, with different matrix elements (Fe, Cu, Ni, Co, Al) and with certified Mn values, were analyzed. Absorption and plasma break-down depend on the solid phase; as a result, there are differences in mass ablation rates that influence the Mn signal response. In order to be able to compare Mn signals, the relative element-dependent response of tested metal matrices was determined from the ablation of Fe, Cu, Ni, Co, and Al pure metal targets. Relative sensitivity factors (RSFs), calculated as the ratio of the signal intensity of 59Co, 58Ni, 63Cu, and 27Al to the signal intensity of 56Fe, were: 0.79, 0.71, 0.74, and 0.51, respectively. All the isotope signals were matched to the value that should correspond to the relative abundance of 56Fe (91.75%). These experimentally determined RSFs were applied for compensating the observed differences. For quantitative measurements a set of CRM carbon steel samples (SS-451/1 to SS-460/1), with Fe contents of approximately 98%, was used for calibration. The samples with different matrices were measured using the main matrix element as internal standard; for this purpose, the measured intensity was firstly extrapolated, from their content in the sample, to the value that should correspond to a content of 98% and, after, was corrected with the calculated RSF. The developed quantification approach provides manganese results with deviations of 5-10% from the certified values, with relative standard deviations of 3-8%.

Sediment profiles of less commonly determined elements measured by Laser Ablation ICP-MS

Anthropogenic influences on trace element profiles in dated sediments from estuaries have been often documented, with the vast majority of studies focusing on a short list of high-abundance trace elements. Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) provides a new approach that minimizes sample preparation and contamination while yielding data on a much larger list of elements simultaneously. We present concentrations and enrichment factor profiles for 22 elements at a locality that is 50 km southeast of Baltimore, the principal industrial city on Chesapeake Bay. Samples representing deposition over almost the entire 20th century were obtained from two archived cores collected 20 years apart. The following elements exhibit profiles consistent with a strong anthropogenic influence, i.e. enrichment after 1920 followed by decline after ca.1980, possibly reflecting increased regulatory efforts: Mn, Co, Cu, Zn, Ag, Cd, In, Sn, Sb, Te, Tl, Pb and Bi. As expected, the redox-sensitive elements: Mo, Re and U have similar profiles to one another. Previously, the potentially hazardous elements, Ag, In, Sb, Te, Tl and Bi, have been measured only rarely in estuarine sediments and never in Chesapeake Bay. Our discovery that their profiles track those of well-known pollutants underscores a need to investigate their sources, transport and biogeochemical behavior. Several rarely determined trace elements, Ga, Ge and Nb, exhibit trendless profiles, as do the major elements, Ti and Fe.