Long-term stability of synthetic cathinones in dried blood spots and whole blood samples: a comparative study
The long-term stability of four synthetic cathinones in dried blood spots (DBS) were tested and compared with those of whole blood samples.
A method to determine four cathinones (pentylone, butylone, mephedrone and benzedrone) in DBS was developed and validated. For comparison, the traditional liquid-liquid extraction for the same analytes in whole blood was also performed.
The calibration curve was found to be linear over 25–1000 ng/mL for DBS samples, with a limit of quantification (LOQ) at 25 ng/mL. The interday imprecision and bias results [up to 7.1% relative standard deviation (RSD) and 5.8%, respectively] were much lower than the maximum data recommended by SWGTOX guidelines. The validation results were similar to those of whole blood samples, which showed interday imprecision and bias results of up to 8.1%RSD and 12.3%, respectively, with a linear calibration curve between 10 and 1000 ng/mL and LOQ of 10 ng/mL. A stability study to compare the degradation rate between both matrices at three storage temperatures [room temperature (25 °C), 4 and − 20 °C] and during 90 days proved the poor stability of cathinones in whole blood, where the methylenedioxy cathinones displayed better stability than those with ring substituents. DBS allowed detection of synthetic cathinones after much longer periods than in whole blood samples.
DBS proved, therefore, to be an useful alternative technique to store blood samples. Extraction of DBS is easy and analytes remain stable for much longer periods.
KeywordsSynthetic cathinones Dried blood spots (DBS) New psychoactive substances (NPS) Liquid chromatography–tandem mass spectrometry (LC–MS/MS) Long-term stability
We thank the support by the Fundação de Amparo à Pesquisa do Estado de São Paulo—FAPESP [Grant numbers 2015/10650-8]; the Conselho Nacional de Desenvolvimento Científico e Tecnológico—CNPq [Grant number 131780/2017-4] and the Superintendência da Polícia Técnico-Científica.
Compliance with ethical standards
Conflict of interest
There are no financial or other relations that could lead to a conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee (Comitê de Ética em Pesquisa da UNICAMP—CEP, CAAE 8452716.2.0000.5404 and Superintendência da Polícia Técnico-Científica, ofício No. 766/2015/ATS/SPTC-SSP).
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