Rapid and Sensitive Determination of Diacetylpolyamines in Human Fingernail by Ultraperformance Liquid Chromatography Coupled with Electrospray Ionization Tandem Mass Spectrometry

A rapid and sensitive ultraperformance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method has been developed and validated for quantitatively determining diacetylpolyamines in the human fingernail. N¹,N⁸-diacetylspermidine (DiAct-Spd), N¹,N¹²-diacetylspermine (DiAct-Spm) and 1,6-diaminohexane (DAH) [the internal standard (IS)] were extracted from human fingernail samples by a MeOH:5 M HCl solution, followed by 4-(N,N-dimethylaminosulfonyl)-7-fluoro-2,1,3-benzoxadiazole (DBD-F) derivatization, and then separated on an ACQUITY BEH C18 column with a gradient elution of acetonitrile and water containing 0.1% formic acid. The derivatives of the diacetylpolyamines were fully separated within a short run time (3.0 min). The triple quadrupole mass spectrometric detection was performed in the multiple reactions monitoring (MRM) mode by the UPLC-ESI-MS/MS system in the positive ionization mode. MRM using the fragmentation transitions of m/z 455.20 → 100.07, 737.25 → 100.07 and 567.10 → 479.07 in the positive ESI mode was performed to quantify DiAct-Spd, DiAct-Spm and IS, respectively. The calibration curve is between 0.04 ng mL⁻¹ and 10 ng mL⁻¹ for DiAct-Spd and DiAct-Spm. The detection limits (signal to noise ratio of five) were 5–10 pg mL⁻¹. A good linearity was achieved from the calibration curves (r² > 0.9999), and the intra-day and inter-day assay precisions were less than 7.06%. Furthermore, the recoveries (%) of the diacetylpolyamines spiked in the human fingernails were 79.18–97.11. The present method proved that the high sensitivity is characterized by the specificity and feasibility of the sample analysis. Consequently, the proposed method was used to analyze human fingernail samples from 15 lung-cancer patients and 22 healthy volunteers. Diacetylpolyamines were detected from the fingernails of the lung-cancer patients for the first time. The concentration of DiAct-Spd in the lung-cancer patient group tended to be higher than those in the healthy volunteers.