Depth profiling (ICP-MS) study of trace metal 'grains' in solid asphaltenes.

Knowledge of trace metal 'grains' in asphaltenes could play a significant role in enhancing refining and processing of crudes and also in providing useful information on mechanistic and migratory features linked to asphaltenes. These metals originate directly from interaction of oils with source-rock, mineral matter, and formation water and their accumulation in asphaltene matrices could vary from oil well to oil well. Suitable asphaltene samples were subjected to high-performance ICP-MS laser depth profiling (213 nm) to depths of 50 μm at 5 μm intervals.

Terbium sensitized luminescence for the determination of ketoprofen in pharmaceutical formulations.

This paper explores an ultra-sensitive luminescence method for the determination of Ketoprofen (KP) in pharmaceutical formulations. The technique is indirect and exploits the luminescence enhancement of terbium (Tb(3+)) by complexation with KP (Tb(3+)-KP), which was monitored at respective excitation and emission wavelengths of lambda(ex) = 258 nm and lambda(em) = 549 nm. The effect of varying the Tb(3+) concentration and using multiple solvents was examined to determine optimal experimental conditions.