Human plasma ricinine quantification by LC-HRMS after micro-solid-phase elution

A rapid, sensitive and specific method for ricinine identification and quantification in plasma has been developed by LC-HRMS. Deuterated ricinine was used as the internal standard. From 100 μL of plasma, ricinine was extracted using micro-solid-phase elution, which allows a reduced extraction time, by eliminating the evaporation step. Eluate is directly injected into the LC-HRMS system. Chromatographic separation was performed using a reverse-phase C₁₈ column with a 4.5 min gradient elution. The method was validated according to European Medicines Agency guidelines. Linearity was verified between 0.25 and 500.0 ng/mL; the maximum precision calculated was 19.9% for the lower limit of quantitation and 9.6% for quality control, and accuracy was within ± 5.6% of the nominal concentrations. Selectivity, carryover, matrix effect and stability were also verified according to European Medicines Agency guidelines. The method allows the rapid and reliable identification of ricin-exposed victims in case of terrorist attacks or poisonings: three intoxication cases are reported.