A power supply with DC surge and spike protection having additional, optional power conditioning and control functions such as low voltage protection, electro mechanical interferences protection and radio frequency interference protection. The welding flux is particularly formulated for limited pass welding applications which exhibit high impact strength, good slag detachability, low weld metal hydrogen and nitrogen absorption, and facilitates in the formation of smooth and consistent weld beads. The reagent ions enter a chamber and interact with a fluid sample to form product ions. Oral bioavailability of amphetamine is maintained at therapeutically useful doses.