4 research outputs found
A quĆmica e toxicidade dos corantes de cabelo
The market for hair dye involves a growing range of products, which requires greater understanding of hair properties, mechanisms of action and color development. In this work, we present a critical analysis of the classification, physical and chemical characteristics, chemical analysis and toxicological/mutagenic potential of dyes used in the hair dyeing process. A compilation of some studies was carried out, focusing on the available knowledge about these dyes and their effects on the environment and human health
THE CHEMISTRY AND TOXICITY OF HAIR DYES
The market for hair dye involves a growing range of products, which requires greater understanding of hair properties, mechanisms of action and color development. In this work, we present a critical analysis of the classification, physical and chemical characteristics, chemical analysis and toxicological/mutagenic potential of dyes used in the hair dyeing process. A compilation of some studies was carried out, focusing on the available knowledge about these dyes and their effects on the environment and human health
Reagentless Detection of Low-Molecular-Weight Triamterene Using Self-Doped TiO<sub>2</sub> Nanotubes
TiO<sub>2</sub> nanotube electrodes were self-doped by electrochemical
cathodic polarization, potentially converting Ti<sup>4+</sup> into
Ti<sup>3+</sup>, and thereby increasing both the normalized conductance
and capacitance of the electrodes. One-hundred (from 19.2 Ā± 0.1
Ī¼F cm<sup>ā2</sup> to 1.9 Ā± 0.1 mF cm<sup>ā2</sup> for SD-TNT) and two-fold (from ā¼6.2 to ā¼14.4 mS cm<sup>ā2</sup>) concomitant increases in capacitance and conductance,
respectively, were achieved in self-doped TiO<sub>2</sub> nanotubes;
this was compared with the results for their undoped counterparts.
The increases in the capacitance and conductance indicate that the
Ti<sup>3+</sup> states enhance the density of the electronic states;
this is attributed to an existing relationship between the conductance
and capacitance for nanoscale structures built on macroscopic electrodes.
The ratio between the conductance and capacitance was used to detect
and quantify, in a reagentless manner, the triamterene (TRT) diuretic
by designing an appropriate doping level of TiO<sub>2</sub> nanotubes.
The sensitivity was improved when using immittance spectroscopy (Patil
et al. <i>Anal. Chem.</i> <b>2015</b>, <i>87</i>, 944ā950; Bedatty Fernandes et al. <i>Anal. Chem.</i> <b>2015</b>, <i>87</i>, 12137ā12144) (2.4
Ć 10<sup>6</sup> % decade<sup>ā1</sup>) compared to cyclic
voltammetry (5.8 Ć 10<sup>5</sup> % decade<sup>ā1</sup>). Furthermore, a higher linear range from 0.5 to 100 Ī¼mol
L<sup>ā1</sup> (5.0 to 100 Ī¼mol L<sup>ā1</sup> for cyclic voltammetry measurements) and a lower limit-of-detection
of approximately 0.2 Ī¼mol L<sup>ā1</sup> were achieved
by using immittance function methodology (better than the 4.1 Ī¼mol
L<sup>ā1</sup> obtained by using cyclic voltammetry)