High-performance liquid chromatographic analysis of β-carbolines in human scalp hair

A chromatographic method was studied for the quantitation of β-carbolines in hair as potent biomarkers. Under optimal conditions, human scalp hair was enzymatically digested to release analytes effectively. The hair digests were treated with fluorescamine before serial extractions to inhibit the artifactual production of β-carbolines during analysis and purify them selectively, followed by reversed-phase high-performance liquid chromatography with fluorometric detection. Hair samples were found to contain β-carboline and 1-methyl-β-carboline, which were identified by tandem mass spectrometry, but not their reduced form 1,2,3,4-tetrahydro-β-carboline and 1-methyl-1,2,3,4-tetrahydro-β-carboline. Both β-carboline and 1-methyl-β-carboline were quantified in the concentration range of 0.1–10.0 ng/ml. Their mean recoveries from hair digests were 70–72%, and the intra- and inter-assay RSD ranged between 6.0 and 10.3% in spiking experiments with standards (1.0 ng/ml). When quantitatively analyzing scalp hair collected from alcoholics, smokers, non-smokers and autistics, β-carboline and 1-methyl-β-carboline showed the concentrations of ng/mg levels or less which characterized different hair samples. The proposed method will be useful for detecting the in vivo concentration changes of β-carbolines associated with alcohol abuse, smoking behavior and neuropsychiatric disorder.