Application of the flow-through analyses of ammonia and calcium in ice core and fresh water by fluorometric detection

A flow-through analyzer that can determine trace amounts of chemical compon ents in ice cores was examined. To obtain the vertical profiles of ammonia and calcium in the ice core, which can be a measure of the climate change, sensitive fluorescence signals were examined, For the determination of ammo nia, a reaction with o-phthalaldehyde and sulfite salt was performed. This system had the potential to measure down to 2 nM, with a 1-mm ice-core reso lution, equivalent to the thickness of the monthly ammonia profiles during the last interglacial maximum. A trace calcium analyzer was simultaneously examined, with the use of the fluorescent enhancement of Fura2 with a detec tion limit of 15 nM. Ammonia and calcium in the Antarctic ice core showed s imilar variation patterns, different from that of the Greenland ice core. T he ammonia analyzer was also applied to the analysis of lake water. (C) 200 1 John Wiley & Sons, Inc.