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 components 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 ammonia, 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 resolution, 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 detection limit of 15 nM. Ammonia and calcium in the Antarctic ice core showed similar variation patterns, different from that of the Greenland ice core. The ammonia analyzer was also applied to the analysis of lake water. © 2001 John Wiley & Sons, Inc. Field Analyt Chem Technol 5: 29–36, 2001