Application of low-density dispersive liquid-liquid microextraction (LDS-DLLME) to identify new psychoactive substances in plasma by LC-MS/MS

Author(s)

Thais Lino

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
• Defense date: 2019-03-22

Examining board members

José Luiz da Costa; Paulo César Pires Rosa; Carla Beatriz Grespan Bottoli

• Advisor: José Luiz da Costa; Marcos Nogueira Eberlin

Abstract

New psychoactive substances (NPS) are synthetic drugs of abuse that provide users with effects similar to those produced by "traditional" substance abuse drugs, but most are not controlled by international agencies and agencies. Currently, the use of NSP has become a major public health problem worldwide, it has been reported of severe poisoning and deaths resulting from the abusive use of these increasingly recurrent drugs. Because of the effectiveness of NSP at low doses, the concentration in highly complex biological matrices such as blood, plasma, urine, oral fluid and hair of such compounds is generally below the detection limit of most analytical methods. Therefore, its necessary that the analytical procedure that involves from the preparation of samples to the analytical instrumentation is adequate to detect and quantify the analytes unequivocally. Regarding the disadvantages of traditional extraction techniques, miniaturized techniques have been gaining a focus due to their advantages in terms of efficiency and low cost, as well as being quicker and easier preparation procedures. The coupling of liquid chromatography with mass spectrometry (LC-MS) in addition to enabling the development of efficient methods and reduced analysis time, offers high selectivity and detectability, and has become one of the most widely used techniques in the field of toxicology in analysis of drugs of abuse in biological matrices. The objective of this project was to optimize, validate and implement a qualitative analytical methodology combining DLLME with the LC-MS technique for the identification of NSP in plasma samples. Analyses were performed in multiple reaction monitoring (MRM), utilizing electrospray ionization (ESI) in positive mode. Qualitative validation was performed following SWGTOX guideline. The LOD ranged from 0.1 to 1 ng/mL, concentrations expected to be found in real cases. The imprecisions were lower than 20% (expressed in terms of repeatability). The values of matrix effects that are within the acceptable range of ± 20% ranged from 1.6 to 13.4% for SC; 0.7 to 8% for FD and from 8.6 to 14.9% for the NBOMes. The recovery of the analytes after the extraction method presented values between 29.8 and 114.4% for all the analytes. For stability analyzes, the 0, 4, 7 and 15 day intervals were evaluated, in which the analytes were mostly decreased, with variations greater than ± 20%. The method was sucessfully applied to ten samples from suicide attempt cases. The LDS-DLLME technique provided satisfactory results for the purpose of the study and can be widely used in clinical and forensic toxicology laboratories, according to the qualitative validation parameters evaluated. In addition, it¿s combined with the use of a sophisticated and complete analytical technique such as LC-MS, which allows for a greater and more reliable identification of NSPs, which have become a worldwide challenge due to their wide variety (AU)

• FAPESP's process: 17/12850-0 - Aplication of low-density dispersive liquid-liquid microextraction (LDS-DLLME) to identify new psychoactive substances in plasma by LC-MS/MS
• Grantee: Thais Lino da Silva
• Support Opportunities: Scholarships in Brazil - Master