RESUMEN
A challenge for detecting phthalates in commercial products such as cheese powders is that the composition of the products is highly complex, and current methods for detection rely on gas chromatography-mass spectrometry, which is not portable and cannot be used by individual consumers at a time and place of their choosing. Herein, we report the development of a new method for phthalate detection in cheese powder using cyclodextrin-promoted fluorescence detection, in which the presence of the phthalate analytes leads to highly analyte-specific changes in the fluorescence emission signal of a fluorophore bound in a cyclodextrin cavity. This method relies on subtle changes in the analyte affinity for the fluorophore and the cyclodextrin cavity and provides for markedly more straightforward sample preparation procedures and an extremely rapid read-out signal, with potential for the development of portable fluorescence sensors. Using this method, we were able to detect 15 phthalate esters with highly analyte-specific responses and at concentrations as low as 0.12 µM, which is well below regulatory levels of concern. Computational investigations strongly support the observed experimental trends.
RESUMEN
This population study was conducted to assess the frequency of physical, microscopical, and chemical properties of automotive paint chips. Population studies of trace evidence provide valuable analytical data for criminalists to assess evidentiary significance. Two-hundred automotive paint chips were collected from auto body shops from the Northeastern United States. All samples were analyzed using stereomicroscopy, brightfield, and polarized light microscopy. Red paints were targeted for further analysis using a sequence of modern instrumental techniques commonly used by forensic paint examiners: Fourier-transform infrared (FT-IR), Raman, and ultraviolet-visible (UV-Vis) microspectroscopy. The discrimination potential of each analytical method was evaluated by inter-comparing the paint samples. Results demonstrated that macroscopic and microscopic properties were able to differentiate 99.995% of the population (one undifferentiated pair out of 19,900). When combined with either FT-IR or UV-Vis microspectroscopy, all paints were differentiated. The results of this research lead to the conclusion that one would not expect to encounter two indistinguishable paint chips originating from different sources during the investigation of a single event.
