Quantification of ricinine in rat and human urine: a biomarker for ricin exposure.

Ricin is a toxalbumin derived from the castor bean plant, Ricinus communis. Ricinine is an alkaloid (3-cyano-4-methoxy-N-methyl-2-pyridone) that shares a common plant source with ricin, and its presence in urine infers ricin exposure. A new quantification method for ricinine was developed that uses solid-phase extraction to prepare 1-mL urine samples (81% recovery) for a 5-min, isocratic high-performance liquid chromatography method, followed by electrospray ionization tandem mass spectrometry. Protonated molecular ions were selected in the multiple reaction monitoring mode and quantified by isotope dilution with (13)C(6)-labelled ricinine as the internal reference. Urine pools enriched with ricinine at two concentrations were characterized as quality control materials and then used to validate the method. The method limit of quantification was 0.083 ng/mL, even with a confirmation ion of low relative abundance. Ricinine was stable in human urine when heated at 90 degrees C for 1 h, and during storage at 25 degrees C and 5 degrees C for 3 weeks. The method was applied to an animal exposure study, a crude ricin preparation scheme, and a forensic analysis. These studies show that ricinine can be measured in rat urine at least 48 h after exposure. Ricinine is present in crude preparations of ricin, and it can be found in human urine after a lethal exposure to ricin.

Quantitation of biomarkers of exposure to nitrogen mustards in urine from rats dosed with nitrogen mustards and from an unexposed human population.

The nitrogen mustards bis(2-chloroethyl)ethylamine (HN1), bis(2-chloroethyl)methylamine (HN2), and tris(2-chloroethyl)amine (HN3) have the potential to be used as chemical terrorism agents because of their extreme vesicant properties. We modified a previously reported method to incorporate automated solid-phase extraction, improve chromatography, and include the urinary metabolite for HN3. The improved method was used to measure levels of the urinary metabolites N-ethyldiethanolamine (EDEA), N-methyldiethanolamine (MDEA), and triethanolamine (TEA) in rats dosed with HN1, HN2, and HN3, respectively, and to establish background levels of EDEA, MDEA, and TEA in human urine samples from a population with no known exposure to nitrogen mustards. Rat dosing experiments confirmed that EDEA, MDEA, and TEA could be detected in urine for at least 48 h after exposure to HN1, HN2, and HN3, respectively. Substantial amounts of EDEA (89 ng/mL), MDEA (170 ng/mL), and TEA (1105 ng/mL) were measured in the urine of rats exposed to 10 mg HN1, HN2, and HN3, respectively, 48 h after exposure. The background concentrations for TEA in the human population ranged from below the limit of detection (LOD 3 ng/mL) to approximately 6500 ng/mL. Neither EDEA (LOD 0.4 ng/mL) nor MDEA (LOD 0.8 ng/mL) was detected above the LOD in the human samples.