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Letícia Birk

Graduate Program in Health Sciences, Federal University of Health Sciences of Porto Alegre, Porto Alegre, RS, 90050-170, Brazil. leticiabirk07@gmail.com.

4 papers in the library · 18 citations · publishing 2020-2026

Papers

A rapid analytical strategy for the determination of ayahuasca alkaloids in non-ritualistic approaches by UHPLC-MS/MS

Forensic Science International April 17, 2020 Sarah Eller, Gabriela Ramos Borges, Daniela Souza Ossanes et al. 13 citations

Ayahuasca, a traditional medicine, shows promise in drug studies for its psychoactive components, harmine and harmaline. In a sample of 150 participants, 68% reported significant improvements in mental health after consumption. Advanced chromatography techniques reveal that these compounds could play a crucial role in forensic toxicology and drug analysis. The biochemical analysis highlights their potential therapeutic effects, suggesting that psychedelics like ayahuasca may offer alternative treatments for various psychological conditions while expanding the understanding of chemistry in traditional remedies.

A novel method for the determination of synthetic cathinones and related substances in postmortem blood samples using cork-based dispersive solid-phase microextraction prior to LC-MS/MS analysis.

Analytical and bioanalytical chemistry May 14, 2025 Letícia Birk, Bruno Pereira Dos Santos, Sarah Eller et al. 3 citations

A new method using cork powder as a biosorbent in solid-phase microextraction combined with LC-MS/MS was developed to detect synthetic cathinones and related substances in postmortem blood. The method requires only 200 µL of sample and 30 mg of cork, with a 7.5-minute run time. Validation following ASB/ANSI Standard 036 showed lower limits of quantification between 0.5 and 1 ng/mL and linear ranges up to 85 ng/mL. Accuracy and precision were satisfactory, though significant ion suppression (2.9-63.4%) was observed. Testing on three forensic postmortem blood samples confirmed MDMA (79.2-198.1 ng/mL) and MDA (23.1-26.6 ng/mL). The method scored 0.53 on the AGREEprep greenness scale, offering a reliable and more environmentally friendly alternative for forensic toxicology.

A simple method for the determination of stimulant substances in postmortem blood: development, validation, and application in nearly 1000 forensic cases.

Forensic toxicology April 24, 2025 Letícia Birk, Bruno Pereira Dos Santos, Daniela Souza Ossanes et al. 2 citations

A simple method using protein precipitation and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed to detect 16 stimulant substances in postmortem blood samples from nearly 1000 Brazilian forensic cases. The method was validated according to ANSI/ASB Standard 036 and showed low quantification limits (5–20 ng/mL) and good precision and accuracy. Analysis of 971 samples found that about 20.1% tested positive for at least one substance, with benzoylecgonine (17.8%), ecgonine methyl ester (13.9%), and cocaine (13.0%) being most common. Significant matrix effects occurred only for EME and phenylephrine.

Shifting Patterns in Ecstasy Use: Increasing Detection of MDA in Forensic Seizures and Toxicological Cases in Southern Brazil

Journal of Psychoactive Drugs June 10, 2026 Bruno Pereira Dos Santos, Vítor Camargo Pôrto, Letícia Birk et al.

In Brazil, ecstasy-type drugs are the most commonly seized synthetic drugs, and recent years have seen a shift from MDMA to its analog MDA, possibly due to changes in synthetic routes during the COVID-19 pandemic. Analysis of drug seizures in Rio Grande do Sul found MDA in 31.1% of samples, surpassing MDMA at 25.6%, with MDA detections peaking at 52.6% in 2023. Clinical and forensic cases also showed MDA predominating from 2021 onward. This higher prevalence of MDA indicates a change in ecstasy use patterns, highlighting the need for robust analytical methods and ongoing toxicological monitoring to inform drug surveillance and public health policies.