Background: New Psychoactive Substances (NPS) belong to several chemical classes,
including phenethylamines, piperazines, synthetic cathinones and synthetic cannabinoids. Development
and validation of analytical methods for the determination of NPS both in traditional and alternative
matrices is of crucial importance to study drug metabolism and to associate consumption to clinical
outcomes and eventual intoxication symptoms. Among different biological matrices, hair is the one
with the widest time window to investigate drug-related history and demonstrate past intake.
Method: The aim of this paper was to overview the trends of the rapidly evolving analytical methods
for the determination of NPS in hair and the usefulness of these methods when applied to real cases.
A number of rapid and sensitive methods for the determination of NPS in hair matrix has been
recently published, most of them using liquid chromatography coupled to mass spectrometry. Hair
digestion and subsequent solid phase extraction or liquid-liquid extraction were described as well as
extraction in organic solvents. For most of the methods limits of quantification at picogram per
milligram hair were obtained.
Results: The measured concentrations for most of the NPS in real samples were in the range of
picograms of drug per milligram of hair. Interpretation of the results and lack of cut-off values for the
discrimination between chronic consumption and occasional use or external contamination are still
Conclusions: Methods for the determination of NPS in hair are continually emerging to include as
many NPS as possible due to the great demand for their detection.