[Highly sensitive determination of three kinds of amanitins in urine and plasma by ultra performance liquid chromatography-triple quadrupole mass spectrometry coupled with immunoaffinity column clean-up].

Cases of toxic mushroom poisoning occur frequently in China every year. In particular, mushrooms containing amanitins can cause acute liver damage, with high mortality rates. The symptoms of acute liver damage are experienced 9-72 h after consumption of the mushrooms. At this time, the concentration of amanitins in blood and urine is too low to be detected even by the highly sensitive ultra performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS/MS), thus rendering clinical diagnosis and treatment difficult. To this end, a method was developed for the determination of -amanitin, -amanitin and -amanitin in urine and plasma by UPLC-MS/MS. Urine and plasma samples were extracted and cleaned up by using an immunoaffinity column. A sample of 2.00 mL urine or 1.00 mL of plasma was diluted with 8.00 mL of phosphate buffer solution (PBS) and then loaded onto the immunoaffinity column at a flow rate of 0.5-1.0 mL/min. After washing the column with 10 mL of PBS and 13 mL of water successively, the bound amanitins were eluted with 3.00 mL of methanol-acetone (1∶1, v/v). The eluent was dried under nitrogen at 55 ℃. The residue was dissolved in 100 μL of 10% (v/v) methanol aqueous solution. The amanitins in urine were concentrated 20 times, while those in plasma were concentrated 10 times. Chromatographic separation was performed on a Kinetex Biphenyl column (100 mm × 2.1 mm, 1.7 μm) with gradient elution using methanol and 0.005% (v/v) formic acid aqueous solution as mobile phases. The three amanitins were detected by negative electrospray ionization tandem mass spectrometry in the multiple reaction monitoring (MRM) mode and quantified by the solvent standard curve external standard method. Method validation was performed as recommended by the European Drug Administration (EMEA). Four levels of quality control (QC) samples were prepared, which covered the calibration curve range, viz., the limit of quantification (LOQ), within three times the LOQ (low QC), medium QC, and at 85% of the upper calibration curve range (high QC), and used to test the accuracy, precision, matrix effect, extraction recovery, and stability. The calibration curves for the three amanitins showed good linear relationships in the range of 0.1-200 ng/mL, and the correlation coefficients () were greater than 0.999. The matrix effects and extraction efficiencies of the three amanitins in urine and plasma were 92%-108% and 90%-103%, respectively, and the coefficients of variation were less than 13%. The accuracies of the three amanitins in urine were within -9.4%-8.0%. The repeatability and intermediate accuracies were 3.0%-14% and 3.5%-18%, respectively. When the sampling volume was 2.00 mL, the limits of detection of the three amanitins in urine were 0.002 ng/mL. The accuracies of the three amanitins in plasma were within -13%-8.0%. The repeatability and intermediate accuracies were 3.9%-9.7% and 5.5%-12%, respectively. When the sampling volume was 1.00 mL, the limits of detection of the three amanitins in plasma were 0.004 ng/mL. The developed method is simple, sensitive, and accurate. During toxic mushroom poisoning detection, 0.0067 ng/mL of -amanitin and 0.0059 ng/mL of -amanitin were detected in the urine of poisoned patients 138 h after ingesting poisonous mushrooms. This method has successfully solved the problem of detecting ultra-trace levels of amanitins in the urine and plasma of poisoned patients. It has important practical significance for the early diagnosis, early treatment, and mortality reduction of suspected poisoning patients. This method can also provide reliable technical support for future research on the toxicological effects and in vivo metabolism of these toxins.