Quantitative Mass Barcode-Like Image of Nicotine in Single Longitudinally Sliced Hair Sections from Long-Term Smokers by Matrix-Assisted Laser Desorption Time-of-Flight Mass Spectrometry Imaging

The matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometric technique (IMS) offered a new breakthrough perspective in the analysis of drug abuse in forensic science; however, it only produced barcode-like images, semi-quantitative analysis. In order to develop intermittent monitoring by this IMS for forensic and medical sciences, it is important to quantitatively measure the contents of longitudinally sliced hair sections. We developed quantitative imaging mass spectrometry (QIMS) of nicotine (NC) in longitudinally sliced hairs by MALDI-IMS with the selected reaction monitoring mode using a labeled NC ((13)C3-NC) standard for the serially chronological monitoring and traceability of NC intake in heavy smokers. The calibration curve of NC/(13)C3-NC was virtually a linear equation at ranges from 1 to 50 ng/mL, the slope was 0.020, and the intercept was almost 0.023 and the R(2) was 0.9965. The limit of quantitation of NC was calculated as 1.6 ng/mg hair (an average weight of the hair would be assumed 0.06 mg/cm) by QIMS. Moreover, NC concentrations in two separate heavy smokers (n = 3) were 8.5 ± 1.2 and 34.5 ± 2.8 ng/mg hair, respectively, and covariations were ∼10% using a single hair. Quantitative mass barcode-like image of sliced section of hair allowed for the quantitative assessment of NC concentrations in long-term smokers similar to drugs and medicines during drug histories.