Final answer:
Rohypnol detection involves toxicological screening, typically immunoassay tests initially, followed by more sensitive methods like GC-MS or LC-MS/MS for definitive diagnosis.
Step-by-step explanation:
The diagnosis that a person has been drugged with rohypnol, also known as flunitrazepam, is generally made through toxicological screening. Specifically, the drug can be detected in the blood or urine of the individual. As rohypnol is a benzodiazepine, it can be identified using immunoassay screening tests, which are designed to detect the presence of specific drug compounds or their metabolites. However, rohypnol is infamous for its rapid metabolism, which can render it undetectable within a short period, particularly in urine. Therefore, to confirm the presence of rohypnol, more sensitive tests such as gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS) may be required. These methods can detect even trace amounts of the substance or its metabolites, providing a definitive diagnosis.