Application of silver-assisted laser desorption ionization ultrahigh-resolution mass spectrometry for the speciation of sulfur compounds.

We herein report the optimization and application of silver cationization (Ag+) in combination with laser desorption ionization (LDI) ultrahigh-resolution mass spectrometry (UHR-MS) to determine the structures of the sulfur-containing compounds present in heavy crude oil. A number of sulfur-containing model compounds were used to optimize the positive-ion mode LDI-MS conditions in the presence of a silver-complexing agent. Under the optimized LDI conditions, sulfur-rich heavy oil fractions were treated with the silver salt, where Ag+ coordinated with the sulfur atoms to speciate the sulfur species. The obtained results suggested that benzothiophenic, naphtheno-non-aromatic sulfides, and non-aromatic thiols were the major components present in the analyzed oil sample. Graphical abstract.

Double Decker anterior cruciate ligament avulsion.

Distal anterior cruciate ligament avulsion from tibial side is an unusual injury. It can be either bony avulsion, which is more common, or rarely a soft tissue peeling of tibial spine with no bone injury. This case report represents a very infrequent injury of combined soft tissue peeling of distal anterior cruciate ligament along with bony avulsion of tibial spine in a 12-years-old boy after falling from his bike.