A liquid chromatography–tandem mass spectrometry method for the determination of nodularin-R in human plasma and its preliminary clinical application

BackgroundNodularins are an important class of hepatotoxic cyclic pentapeptides that most current methods are ill-suited to clinically monitor. Therefore, a liquid chromatography–tandem mass spectrometry (LC/MS/MS) assay for the determination of nodularin-R in human plasma was validated and applied to clinical samples in this report.MethodsSample cleanup and enrichment were achieved using solid phase extraction. The concentration of nodularin-R in each sample was calculated using the relative abundance area ratio of nodularin-R and a stable isotope-labeled internal standard.ResultsThe validated calibration range was from 0.50 to 100 ng/ml. The intra- and inter-day precision were < 6.0 and 9.8%, respectively. The accuracy at the lower limit of quantification (LLOQ) was 2.0%, while for other QC levels, it was < 3.4%. The absolute concentrations determined by the LC/MS/MS assay were significantly lower than those measured using a commercial immunoassay. Finally, a variety of demographic factors were evaluated and the findings indicated that the elderly (> 50 y) and people living close to seashore or lakefront areas (≤ 10 km) were the most susceptible to nodularin-R (p = 0.79 × 10− 4 and 2.57 × 10− 6, respectively).ConclusionsThis report was among the first to demonstrate that clinical monitoring of nodularin-R could be achieved using LC/MS/MS.

► An LC/MS/MS assay for the determination of nodularin-R in human plasma was validated and applied.
► The LC/MS/MS assay was compared with a commercial immunoassay.
► Demographic factors (i.e., sex, age, body mass index (BMI) and area of residence) were evaluated.
► This report demonstrated that clinical monitoring of nodularin-R could be achieved using LC/MS/MS.