No abstract

Surface-enhanced Raman spectroscopy (SERS) at a silver electrode was used to obtain the Raman spectrum of lumazine free of interference from fluorescence. The study was carried out varying the experimental conditions of voltage and pH. SERS spectra were compared with Fourier transform infrared (FTIR), coherent anti-Stokes Raman spectroscopy (CARS), normal Raman spectroscopy (NRS), and ultraviolet resonance Raman spectroscopy (UV RRS) spectra. Ab initio calculations at the Hartree−Fock/6-31G(d) level were made of the vibrational spectra of lumazine [2,4(3H,8H)-pterdinedione, LUM] and dimethyllumazine [6,7-dimethyl-,2,4(3H,8H)-pterdinedione, DML], and these were compared with the experimental results. Band assignments were made for LUM and DML. In addition, to determine the structure of the molecules on the metal surface as well as to examine the effects of the surface on the observed spectrum, we compared the results with the FTIR spectrum of a known metal complex of LUM. We also analyzed band shifts and the intensity ratio of in-plane and out-of-plane modes as a function of potential. This analysis indicates that the LUM molecules are tilted at an angle of ca. 45° (0.0 to −0.3 V) to the surface interacting as dimers with silver (Ag) sites through the lone pairs on the 1N or 5N atoms of the LUM ring. The tilt angle moves to ca. 50° as the potential is made more negative (−0.6 to −0.7 V).

No abstract

Intoxications, as a rule, are related to the medical-legal area; some toxic agents occupy prominent place as the main ones responsible for the occurrence of deaths. In legal medicine, both human and animal, the major challenge faced is the elucidation of the cause of death and the time of death when corpses are found, indicating possible exposure to toxic agents, which are intentionally added most often, in order to cause irreversible damage to the victim. In this context the methods of toxicological analysis involving poisoning are widely studied and disseminated, there are numerous literature reviews on analytical validation processes in the most diverse areas, but reviews of forensic literature are scarce and outdated. Wrong or even unreliable analytical reports can lead to misleading conclusions, culminating in irreparable financial, academic or judicial damages. Since the validation processes are essential in laboratory routines and that forensic analytical methods applied in the legal area are important for the elucidation of xenobiotic intoxication tables, the purpose of this review is to discuss validation processes with a focus on analysis forensic, since the results from this type of analysis must be irrefutable and unequivocal and an error of result