Abstract
A Flow Injection Analysis (FIA) spectrofluorimetric method for calcium determination in ice cores was optimised in order to achieve better
analytical performances which would make it suitable for reliable calcium measurements at ppt level.
The method here optimised is based on the formation of a fluorescent compound between Ca and Quin-2 in buffered environment. A careful
evaluation of operative parameters (reagent concentration, buffer composition and concentration, pH), influence of interfering species possibly
present in real samples and potential favourable effect of surfactant addition was carried out. The obtained detection limit is around 15 ppt, which is
one order of magnitude lower than the most sensitive FlowAnalysis method for Ca determination currently available in literature and reproducibility
is better than 4% for Ca concentrations of 0.2 ppb.
The method was validated through measurements performed in parallel with Ion Chromatography on 200 samples from an alpine ice core (Lys
Glacier) revealing an excellent fit between the two chemical series. Calcium stratigraphy in Lys ice core was discussed in terms of seasonal pattern
and occurrence of Saharan dust events.
© 2007 Elsevier B.V. All rights reserved.