The assessment of chlorine, fluorine, and sulfur concentrations in depth profile of drill cuttings was performed using ion chromatography after sample preparation by pyrohydrolysis. The parameters for pyrohydrolysis were optimized using a Box-Behnken design, and the established conditions were 300 mg of sample, 300 mg of V2O5, temperature of 1000 °C, reaction time of 25 min, and absorbing solution of 50 mmol L-1 NH3 + 150 mmol L-1 H2O2. The accuracy was evaluated by the analysis of certified reference materials and recovery tests, and the results showed a good agreement between determined and certified values and recoveries (89-108%). The precision (relative standard deviation (RSD) < 10%), and the limits of detection (0.5-2.5 mg kg 1) were suitable for drill cuttings analysis. The concentration of chlorine, fluorine, and sulfur in drill cuttings at different depths was at mg g-1 range, and its variation is related to the mineral composition of the samples.

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%.