ABSTRACT
A method for the determination of methylmercury ( MeHg ) and ethylmercury ( EtHg ) in aquatic products was developed using gas chromatography-mass spectrometry with stable isotope-labelled internal standard. After ultrasonication assisted hydrochloric acid extraction, MeHg and EtHg in samples were extracted into toluene under the presence of sodium chloride and then back-extracted into cysteine aqueous solution. The MeHg and EtHg were released from their complexes with cysteine by adding cupric ions, and then derived with sodium tetraphenylborate. Under the optimal chromatographic conditions, MeHgPh and EtHgPh, the resulting derivatives, were separated completely on a DB-5MS capillary column and detected by electron impact ionization mass spectrometry in the selective ion monitoring ( SIM) mode, and quantified by a stable isotope dilution method using the d3-methylmercury as internal standard. The calibration curves were linear in the range of 1-500 μg/L of MeHg and EtHg. Concentration of 0. 828 mg Hg/kg with relative standard deviation ( RSD ) of 3 . 2% ( n=6 ) was obtained for MeHg in GBW 10029 . This was in good agreement with the certified values of (0. 84±0. 03) mg Hg/kg. The average recoveries were 94%-101% and 81%-104% for MeHg and EtHg spiked in aquatic samples, with RSDs of 1. 9%-4. 7% and 3. 1%-8. 2%(n=6), respectively. The limits of detection (S/N=3) of the two targets were 0. 1-0. 3μg/kg. This method was sensitive, accurate and could meet the demand of the determination of methylmercury and ethylmercury in aquatic products.
ABSTRACT
El timerosal es un derivado del mercurio utilizado desde 1930 como preservante de vacunas. En las últimas décadas ha sido cuestionada su seguridad, especialmente por la posibilidad de toxicidad neurológica. La revisión de varios estudios realizados en niños que recibieron vacunas que contienen timerosal y la posición de organismos de expertos internacionales en relación al uso de este compuesto en vacunas, permite al Comité Consultivo de Inmunizaciones concluir que no existe evidencia de eventos adversos en lactantes o niños por exposición al timerosal contenido en vacunas rutinarias y, por lo tanto, no habría razón para modificar las actuales prácticas de inmunización en Chile.
Thimerosal is a mercury derivative included in vaccines since 1930 with the aim to prevent microbial contamination. During the last decades, the use of thimerosal has been questioned, specifically because of a potential association with neurotoxicity. After a thorough review of published studies on pediatric use of thimerosal-containing vaccines, and of position papers from international expert groups, the Consultive Committee of Immunizations of the Chilean Society of Infectious Diseases concludes that there is no solid evidence of adverse events associated with the use of thimerosal containing vaccines in infants and children. Therefore, a change in current vaccine practices refererred to thimerosal-containing vaccines is not justified in Chile.