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- Exploring the potential of a MEPS/UHPLC-based methodology on the Exploring the potential of a MEPS/UHPLC-based methodology on thePublication . Berenguer, Pedro; Camacho, Irene C; Câmara, José S.; Câmara, Rita; Oliveira, SusanaAsthma is a heterogeneous disease characterized by chronic inflammation and long term irreversible remodeling of the airways. The enzymatic peroxidation of the arachidonic acid is part of the pathophysiology of this disease and leads to the formation of powerful inflammatory mediators, characteristic of asthma. The present work aimed to develop an easy-to-use ultra-high pressure liquid chromatography (UHPLC)-based strategy in order to characterize lipid peroxidation biomarkers: leukotrienes E4 (LTE4) and B4 (LTB4) and 11β-prostaglandin F2α (11βPGF2α), eicosanoids present in the urine of asthmatic patients and healthy individuals (control group). A semi-automatic eVol®-microextraction by packed sorbent (MEPS) format was developed in order to isolate the target analytes. The method was fully validated under optimal extraction (R-AX sorbent, 3 conditioning-equilibration cycles with 250 μL of ACN-H2O at 0.1% FA, 10 extract-discard cycles of 250 μL of sample at a pH of 5.1, elution with 2 times 50 μL of MeOH and concentration of the eluate until half of its volume) and chromatographic conditions (14-min analysis at a flow rate of 300 μL min-1 in an UHPLCPDA equipped with a BEH C18 column). Our results indicated good recoveries (>95%) in addition to excellent extraction efficiency (>95%) at three concentration levels (low, mid and high) with precision (RSDs) less than 11%. The lack-of-fit, goodness-of-fit and Mandel’s fitting tests, revealed good linearity within the concentration range. Good selectivity and sensitivity were achieved with limits of detection ranging from 0.04 ng mL-1 for LTB4 to 1.12 ng mL-1 for 11βPGF2α, and limits of quantification from 0.10 ng mL- 1 for the LTB4 to 2.11 ng mL-1 for 11βPGF2α. The developed method was successfully applied to the urine of asthmatic patients and healthy individuals. On average, the urine of asthmatic patients present significantly higher concentrations of 11βPGF2α (112.96 ng mL-1 vs 62.56 ng mL-1 in control group), LTE4 (1.27 ng mL-1 vs 0.89 ng mL-1 in control group) and LTB4 (1.39 ng mL-1 vs 0.76 ng mL- 1 in control group). These results suggest the potential of the target eicosanoids and the developed method on asthma diagnosis and on the follow-up of the therapeutic response.
- Structure assignment of seized products containing cathinone derivatives using high resolution analytical techniquesPublication . Gonçalves, João; Alves, Vera; Aguiar, Joselin; Caldeira, Maria J.; Teixeira, Helena M.; Câmara, José S.The innovation of the new psychoactive substances (NPS) market requires the rapid identification of new substances that can be a risk to public health, in order to reduce the damage from their use. Twelve seized products suspected to contain illicit substances were analyzed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), gas chromatography coupled to mass spectrometry (GC-MS), and nuclear magnetic resonance spectroscopy (NMR). Synthetic cathinones (SCat) were found in all products, either as a single component or in mixtures. Infrared spectra of all products were consistent with the molecular structure of SCat, showing an intense absorption band at 1700-1674 cm-1, corresponding to the carbonyl stretching, a medium/strong peak at 1605-1580 cm-1, indicating stretching vibrations in the aromatic ring (C=C) and bands with relative low intensity at frequencies near 2700-2400 cm-1, corresponding to an amine salt. It was possible to identify a total of eight cathinone derivatives by GC-MS and NMR analysis: 4'-methyl-α-pyrrolidinohexanophenone (MPHP), α-pyrrolidinohexanophenone (α-PHP), 3-fluoromethcathinone (3-FMC), methedrone, methylone, buphedrone, N-ethylcathinone, and pentedrone. Among the adulterants found in these samples, caffeine was the most frequently detected substance, followed by ethylphenidate. These results highlight the prevalence of SCat in seized materials of the Portuguese market. Reference standards are usually required for confirmation, but when reference materials are not available, the combination of complementary techniques is fundamental for a rapid and an unequivocal identification of such substances.