A determinação de elementos terras raras (REE) em catalisadores gastos provenientes da indústria de petróleo é proposta. Foram testados três procedimentos de tratamento de amostra, um sem adição de HF e outros dois usando diferentes quantidades de HF e ácido bórico, além de uma etapa de evaporação assistida por radiação micro-ondas para dissolução dos fluoretos de REE. O meio contendo 1,0 mL de HF e 8,0 mL de ácido bórico foi eficiente para promover a completa digestão da amostra. Estudos foram realizados usando uma célula de reação para redução de interferências por íons poliatômicos para quatro elementos por espectrometria de massas com plasma acoplado indutivamente (ICP-MS). Material de referência certificado, TDB-1, foi utilizado para avaliar a exatidão do método aplicado a dez amostras de catalisadores. O procedimento proposto é rápido, eficiente e apresentou exatidão e precisão adequadas para 14 dos 16 analitos determinados. Testes de adição e recuperação apresentaram valores entre 87% e 101%.

The determination of rare earth elements (REE) in spent catalyst samples from oil refinery is proposed. Three sample treatment procedures were tested, one without HF and two using different amounts of HF and boric acid. A microwave evaporation step to promote the dissolution of the REE fluorides was carried out. The medium containing 1.0 mL of HF and 8.0 mL of boric acid promoted the complete digestion. Studies were carried out using a reaction cell to overcome polyatomic interferences on four elements by inductively coupled plasma mass spectrometry (ICP-MS). Certified reference material, TDB-1, was used to evaluate the method accuracy applied to ten spent catalysts. The sample treatment is fast and promotes the complete digestion of the samples and the developed procedure led to proper accuracy for 14 of the 16 determined analytes. Recovery tests presented values between 87% and 101%.

A method was developed for quantification of Cd and Pb in ethanol fuel by filter furnace atomic absorption spectrometry. Filter furnace was used to eliminate the need for chemical modification, to stabilize volatile analytes and to allow the application of short pyrolysis step. The determinations in samples were carried out against calibration solutions prepared in ethanol. Recovery tests were made in seven commercial ethanol fuel samples with values between 90 and 120%. Limits of detection were 0.1 µg L-1 for Cd and 0.3 µg L-1 for Pb. Certified water samples (APS 1071, APS 1033, NIST 1643d, NIST 1640) were also used to evaluate accuracy and recoveries from 86.8% to115% were obtained.