UHPLC-MS/MS determination of oleandrin in blood and tissues of dairy cattle poisoned by oleander (Nerium oleander)

The accidental ingestion of leaves or cut branches of oleander (Nerium oleander) often results in severe poisoning in cattle. This natural shrub contains oleandrin, a highly toxic cardiac glycoside, which may prove fatal even at very low amounts. For this reason, a highly sensitive ultra-high performance liquid chromatography-tandem mass spectrometry method was developed and validated for in-vivo oleandrin determination in bovine blood and serum samples or in bovine liver and heart for post-mortem diagnosis. The method was highly selective as the mass spectrometer worked in selected reaction monitoring mode using the first five most intense m/z transitions of the oleandrin. The limits of detection and quantitation were 0.11 and 0.36 ng mL-1, respectively, whereas the method detection and quantitation limit values ranged 0.006-0.051 ng g-1 and 0.018-0.154 ng g-1, respectively. The chromatographic run was only 5 min and the time employed for the sample pretreatment (25-30 min) is useful to avoid the presence of matrix effect. All the recovery values were within 62.9-80.5%. The method was successfully used to incurred samples from an accidentally poisoned cow and is expected to be applicable to forensic purposes.