Best confirmatory test for syphilis is

FTA-ABS: FTA-absorption test in which the test serum is preabsorbed with sonicate of the Reiter treponemes to eliminate group-specific reactions. FTA-ABS is as specific as the TPI test and is now accepted as a standard reference test. Ref: Textbook of microbiology; Ananthanarayan and paniker's; 10th edition; Pg:382