Fatal intoxication with N-ethylpentylone: a case report and method for determining N-ethylpentylone in biological material

We present a fully validated method for determination of N -ethylpentylone in biological material and a case report of fatal intoxication with N -ethylpentylone. Blood and urine samples were extracted with ethyl acetate from alkaline medium (pH 9). The analysis was carried out using ultra-high-performance liquid chromatography–tandem mass spectrometry. MDMA- d 5 was used as the internal standard. Validation criteria were evaluated for blank blood and urine at concentrations of 10 and 100 ng/mL. The validation parameters were as follows: lower limit of quantification: 1 ng/mL for blood and urine, coefficient of determination: blood > 0.9996, urine > 0.9975, precision for 10 and 100 ng/mL, respectively: blood 4.87% and 4.47%, urine 1.93% and 2.43%, accuracy for 10 and 100 ng/mL, respectively: blood 14.7% and −2.95%, urine 19.1% and 2.10%, recovery for 10 and 100 ng/mL, respectively: blood 91.5% and 100.2%, urine 97.4% and 96.7%, matrix effect in blood was 127% and 117% for 10 and 100 ng/mL, respectively, in urine 124% and 117% for 10 and 100 ng/mL, respectively. In the present case of fatal intoxication with N -ethylpentylone, the determined concentration of this substance was 10.6 µg/mL in peripheral blood and 17.6 µg/mL in urine. In both materials, four metabolites of N -ethylpentylone were determined qualitatively. The developed method enables the determination of N -ethylpentylone with high sensitivity and selectivity. The method was used to make determinations in biological material in the case of fatal intoxication with N -ethylpentylone.