Cross calibration between XRF and ICP-MS for high spatial resolution analysis of ombrotrophic peat cores for palaeoclimatic studies

Anal Bioanal Chem. 2015 Jan;407(2):379-85. doi: 10.1007/s00216-014-8289-3. Epub 2014 Nov 18.

Abstract

Ombrotrophic peatlands are remarkable repositories of high-quality climatic signals because their only source of nutrients is precipitation. Although several analytical techniques are available for analysing inorganic components in peat samples, they generally provide only low-resolution data sets. Here we present a new analytical approach for producing high-resolution data on main and trace elements from ombrotrophic peat cores. Analyses were carried out on a 7-m-long peat core collected from Danta di Cadore, North-Eastern Italy (46° 34' 16″ N, 12° 29' 58″ E). Ca, Ti, Cr, Fe, Cu, Zn, Ga, Sr, Y, Cd, Ba and Pb were detected at a resolution of 2.5 mm with a non-destructive X-ray fluorescence core scanner (XRF-CS). Calibration and quantification of the XRF-CS intensities was obtained using collision reaction cell inductively coupled plasma quadruple mass spectrometry (CRC-ICP-QMS). CRC-ICP-QMS measurements were carried out on discrete samples at a resolution of 1 cm, after dissolution of 150-mg aliquots with 9 ml HNO3 and 1 ml HF at 220 °C in a microwave system. We compare qualitative XRF-CS and quantitative CRC-ICP-MS data and, however the several sources of variability of the data, develop a robust statistical approach to determine the R (2) and the coefficient of a simple regression model together with confidence intervals. Perfect positive correlations were estimated for Cd, Cr, Pb, Sr, Ti and Zn; high positive correlations for Ba (0.8954), Y (0.7378), Fe (0.7349) and Cu (0.7028); while moderate positive correlations for Ga (0.5951) and Ca (0.5435). With our results, we demonstrate that XRF scanning techniques can be used, together with other well-established geochemical techniques (such as ICP-MS), to produce high-resolution (up to 2.5 mm) quantitative data from ombrotrophic peat bog cores.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calibration
  • Climate
  • Environmental Monitoring / methods
  • Italy
  • Limit of Detection
  • Mass Spectrometry / instrumentation
  • Mass Spectrometry / methods*
  • Metals / analysis*
  • Regression Analysis
  • Soil / chemistry*
  • Spectrometry, X-Ray Emission / instrumentation
  • Spectrometry, X-Ray Emission / methods*

Substances

  • Metals
  • Soil