Quantitative Trace Analysis by Wavelength-Dispersive EPMA |
| |
Authors: | Stephen J B Reed |
| |
Institution: | (1) Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, England, GB |
| |
Abstract: | “Trace” elements may be defined as elements whose concentrations are of a similar order to the detection limit. In WD analysis
the detection limit is a function of the ‘figure of merit’ P2/B, where P is the pure-element peak intensity and B the background intensity. With normal analysis conditions detection limits
of ∼100 ppm are typical, but substantial improvements can be achieved by using higher values of accelerating voltage and beam
current. Long counting times are also advantageous, but should preferably be divided into relatively short alternating peak
and background measurements to minimise the effect of instrumental drift. Using separate routines for trace and major element
analysis is desirable owing to their different requirements. As the statistically defined detection limit is reduced, errors
due to background nonlinearity and interferences (overlaps) from other elemental peaks become more probable. Spectrum simulation
is useful for optimising background offsets and choice of crystal to minimise interferences, and estimating interference corrections
when these are necessary. ‘Blank’ standards containing none of the trace elements of interest are also useful for quantifying
background nonlinearity. |
| |
Keywords: | : Trace analysis WDS EPMA |
本文献已被 SpringerLink 等数据库收录! |
|