Formaldehyde analysis of seized cosmetic products by HS-GC-MS of methylal, ethoxymethoxymethane, and ethylal derivatives

Abstract Formaldehyde is a carcinogenic compound used as preservative in cosmetic products. In this study, a derivatization procedure using MeOH, EtOH and HCl (25:25:1), and incubation at 60ºC for 4 hours was optimized, and the derivatized products - methylal, ethoxymethoxymethane (EMM), and ethylal - were directly analyzed by headspace-gas chromatography-mass spectrometry (HS-GC-MS) to determine formaldehyde concentrations. The validated method provided good linearity of the standard curve, selectivity, recovery (89.6-106.6%), repeatability, and intermediate precision (RSD < 12%), with an LOD of 0.0015% and an LOQ of 0.005% for all derivatized analytes. The validated method showed to be fast, clean, and easy to implement in a laboratory. To the best of our knowledge, this is the first reported HS-GC-MS procedure to determine formaldehyde as methylal, ethylal, and EMM as derivatized compounds. The method was satisfactorily applied for the analysis of nine hair-straightener cream samples seized by the Civil Police of the Federal District, Brazil. Eight samples contained formaldehyde, at levels ranging from 0.33 to 4.02 %, higher than the legal levels, indicating the need to control the levels of this toxic compound in cosmetic products

Nuevos enfoques en la reconstrucción coronaria del diente endodónticamente tratado (DET) / New approaches in the coronal reconstruction of the endodontically treated tooth (ETT)

Los conceptos referidos a la rehabilitación del diente endodónticamente tratado han cambiado sustancialmente. Se acepta como verdadero refuerzo a la misma estructura dentaria, por lo tanto, los procedimientos que la conserven son de elección. Asimismo, se deben diferenciar las situaciones en el sector anterior y posterior de la arcada dentaria, siendo necesaria en el sector anterior una estabilización mecánica con pernos o potes. Será en cambio, más habitual no utilizar dipositivos intrarradiculares en el sector posterior. La integración de superficies que se consigue con los mecanismos adhesivos, permite más ahorro de tejidos. En tanto que las restauraciones (inlays, onlays, coronas y postes no metálicos) elaboradas con materiales más fácilmente integrables (cerámicos y compuestos) cobran mayor importancia en relación con esta filosofía