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This work describes the development of a method to determine cadmium in coal, in which iridium is used as a permanent chemical modifier and calibration is performed against aqueous standards by high-resolution continuum source atomic absorption spectrometry (HR-CS AAS). This new instrumental concept makes the whole spectral environment in the vicinity of the analytical line accessible, providing a lot more data than just the change in absorbance over time available from conventional instruments. The application of Ir (400 microg) as a permanent chemical modifier, thermally deposited on the pyrolytic graphite platform surface, allowed pyrolysis temperatures of 700 degrees C to be used, which was sufficiently high to significantly reduce the continuous background that occurred before the analyte signal at pyrolysis temperatures <700 degrees C. Structured background absorption also occurred after the analyte signal when atomization temperatures of >1600 degrees C were used, which arose from the electron-excitation spectrum (with rotational fine structure) of a diatomic molecule. Under optimized conditions (pyrolysis at 700 degrees C and atomization at 1500 degrees C), interference-free determination of cadmium in seven certified coal reference materials and two real samples was achieved by direct solid sampling and calibrating against aqueous standards, resulting in good agreement with the certified values (where available) at the 95% confidence level. A characteristic mass of 0.4 pg and a detection limit of 2 ng g(-1), calculated for a sample mass of 1.0 mg coal, was obtained. A precision (expressed as the relative standard deviation, RSD) of <10% was typically obtained when coal samples in the mass range 0.6-1.2 mg were analyzed.

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252TINOCO JA ET AL. RESUMO -O objetivo deste trabalho é estabelecer a relação entre a infecção pelo vírus do papiloma humano (HPV) e o desenvolvimento de lesões malignas (carcinoma epidermóide) INTRODUÇÃOAs neoplasias da boca e orofaringe constituem 5% de todas as neoplasias malignas, sendo que destas, 90% são carcinomas espinocelulares. Apesar da exposição da mucosa oral a vários carcinógenos, somente um pequeno percentual dos indivíduos desenvolvem câncer 1 . Lembrando que a carcinogênese é um processo multifatorial, a mutagênese é determinada também por agentes co-carcinogenéticos como o papilomavírus humano (HPV) 2,3 . O epitélio da cavidade oral e orofaringe é uma membrana mucosa com propensão para o desenvolvimento neoplásico, sendo exposto a vários carcinógenos nutricionais e ambientais, determinantes de lesões decorrentes de efeitos da infecção pelo HPV e mutagênese química, sendo que dos 77 tipos de HPV isolados, 41 deles apresentam maior tropismo pelas mucosas. A síntese do DNA viral (diferentes seqüências) ocorre na camada basal do epitélio escamoso, onde a célula neoplásica se desenvolve. Isto ocorre a partir da síntese de três oncogens (oncoproteínas), sendo que a E5 estimula o fator de crescimento epidérmico (FCE), a E6 ligada ao p53 selvagem e a E7 ao Rb selvagem, todas encontradas nos HPV de alto risco (HPV16,18,31,33,35,39,42)