A laboratory can identify acetaminophen in a specimen without establishing how it was taken. A postmortem series illustrates the difference between identifying a compound and linking it to the contents of a particular product.
The study described 47 specimens from 20 autopsies selected for suspected psychoactive substance overdose. The specimens included blood, urine, bile and stomach contents. After extraction, the investigators used gas chromatography–mass spectrometry. One example in the paper shows a spectrum from a blood sample compared with the acetaminophen reference spectrum in the instrument library.
A matching spectrum supports the reported identity in the specimen. It does not determine the amount present or show whether acetaminophen came from a separate medication or a mixture. A reviewer assessing the amount would look for a quantitative result and the calibration supporting it. Connecting it to a particular product would require separate evidence about that product.
Biscevic-Tokic and colleagues, Acta Informatica Medica (2015). Journal article · Full text.