Hair analysis of histamine after fluorescence labeling by column-switching reversed-phase liquid chromatography with electrospray ionization mass spectrometry and application to human hair

Abstract

Sensitive determination of histamine (HA) in hair was carried out by column-switching reversed-phase high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC–ESI–MS). HA was labeled with excess amounts of 4-( N, N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) at 60 °C for 30 min in a mixture of 0.1 M borax (pH 9.3) and acetonitrile (CH 3CN). The resulting DBD–HA derivative was roughly separated by a Mightysil RP-18 GP (100 × 2 mm i.d., 3 μm) with an acidic mobile phase containing 0.1% trifluoroacetic acid. DBD–HA in the fraction flowing due to a position change in the six-port column-switching valve was then completely separated by a Wakopak Navi C30 (150 × 2 mm i.d., 5 μm) with 20 mM AcONH 4–CH 3CN (8:2). The mass spectrometer was operated in the selected reaction monitoring (SRM) mode for the product ion ( m/ z 292) obtained from MS–MS measurement using the protonated molecular ion [M + H] + ( m/ z 337) as the precursor ion. Good linearity was achieved from the calibration curve obtained by plotting peak area ratios of the internal standard (HA– d 4) against the injected amounts of HA (1.66–16.6 pmol, r 2 = 0.999). The coefficients of variation, at 1.66- and 16.6-pmol injections, were 5.6 and 3.7%, respectively ( n = 6). Furthermore, the detection limit was 0.167 pmol. The efficiency of the recommended procedure was identified from the determination in the rat hair root after intraperitoneal administration of HA. The proposed method was applied to HA determination in the hair shaft of Dark Agouti rats and healthy volunteers. The variations in the concentrations in 1 mg of hair shaft were 0.80–1.84 pmol (mean ± SD = 1.33 ± 0.33, n = 12) in rats and 0.94–72.3 pmol (17.2 ± 21.5, n = 16) in humans. The determination of HA in the plasma of rats and humans was also performed successfully by this method. Because the proposed method provides good precision and trace detection of HA in hair, the analytical technique seems to be applicable for the determination of various biogenic amines in hair.