Synchrotron-based x-ray fluorescence applied to invertebrates to investigate the role of essential trace elements in a biological process

Abstract

The fluorescence spectra have been detected by exciting invertebrate individual structures, such as external shell, embedded soft-tissue and operculum, with 8, 10 and 12 keV synchrotron x-rays, to find out about the accumulation of trace elements and biological processes in a small animal shell. A new hard x-ray micro-spectroscopy beamline facility, X27A, available at National Synchrotron Light Source, Brookhaven National Laboratory, USA, was utilized. It provided the primary beam in a small spot of the order of ∼10 μm, for focusing. With this spatial resolution and high flux throughput, the synchrotron-induced x-ray fluorescent intensities were measured using a liquid-nitrogen-cooled 13-element energy-dispersive high-purity germanium detector. The fluorescence spectrum arising from the sample as a whole was assessed. Calcium is predominant in these aquatic organisms and a normal constituent of all living matter. The percentage of calcium is lower in the soft tissue, as distinguished from other samples, and the contributions of Cu and Zn are considerable. The latter possibility is due to some ground-based minerals, which may enter the sample when it traverses the land, and get attached to the soft tissue. This way, the accumulation of biominerals will be enhanced in addition to the originally presented ones. The presence of other bioactive trace elements such as Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Rb and Sr was observed in low proportions. Some of these trace elements, for example, Mn, Fe, Cu, Rb and Sr, may induce toxic effects and the other potentially toxic elements, Ni and As, induce disorder in the organism if present in higher and lower proportions.