In this work, Zn/Al layered double hydroxides intercalated with dodecyl sulfate ion (DS) in molar ratios (Zn2+/Al3+) 2:1, 3:1 and 4:1 were synthesized by co-precipitation method and then they were adsolubilized with essential oil of copaiba in the concentrations of 3, 5, 10, 13 and 15% wt/wt to be used as carriers in therapeutic ointments for skin injury treatments. The XRD results showed a diffraction pattern corresponding to the structure of LDHs with the presence of diffraction peaks referring to the basal reflection planes. Typical stretching and vibration bands of copaiba essential oil in FTIR spectra confirmed the adsolubilization process. The oil release plateau in the ointment was above 80% at normalized values in a time of approximately 20 h, the time required for dissolution and release of molecules adsorbed in the layered structure of the material for molar ratios 2:1 and 3:1 and the release of the solubilized molecules in the interlayer space. In contrast, LDH with a 4:1 molar ratio showed slower release and did not reach the plateau in 48 h, as this material has the ability to retain oil molecules in the LDH for longer, causing a slower release in relation to other molar ratios. The analysis for the non-intercalated copaiba oil showed a gradual increase in the concentration of the oil in the ointment, indicating a different curve profile.

Um método para determinação sequencial de Cu e Fe em material particulado atmosférico (APM) coletado em filtro de fibra de vidro por amostragem em suspensão e espectrometria de absorção atômica com chama é proposto. A otimização do método foi realizada utilizando-se uma massa de amostra seca em pó (filtro + APM) de 50 mg, dispersa em solução de ácido nítrico 0,5 mol L-1 e tratada por 10 min em banho ultrassônico. Os limites de detecção (n = 10) foram 4 e 14 µg g-1 para Cu e Fe no filtro, respectivamente. A repetitividade expressa como desvio padrão relativo foi melhor do que 7 e 8% (n = 3) para Cu e Fe, respectivamente. A exatidão do método foi confirmada analisando-se material de referência certificado de cinzas atmosféricas (BCR 176R). Os resultados obtidos para seis amostras de APM utilizando o método proposto não apresentaram diferenças significativas em comparação com os valores obtidos usando o método de extração ácida e determinação por espectrometria de massas com plasma indutivamente acoplado. O método analítico mostrou-se simples, rápido e confiável.

A slurry sampling flame atomic absorption spectrometric method for sequential determination of Cu and Fe in airborne particulate matter (APM) collected on glass fiber filters is proposed. The method optimization was carried out using a dry powdered sample (filter + APM) mass of 50 mg, dispersed in 0.5 mol L-1 nitric acid solution and under ultrasonic bath for 10 min. The limits of detection (n = 10) were 4 and 14 µg g-1 for Cu and Fe on the filter, respectively. The repeatability expressed as the relative standard deviation was better than 7 and 8% (n = 3) for Cu and Fe, respectively. The accuracy of the method was confirmed by analysis of the fly ash certified reference material (BCR 176R). The results obtained for six samples of APM using the proposed method showed no significant differences with those obtained after microwave-assisted acid extraction and determination by inductively coupled plasma mass spectrometry. The analytical method proved to be simple, fast and reliable.

An on-line method for Cd and Pb pre-concentration and simultaneous determination in acid digested seafood by inductively coupled plasma optical emission spectrometry (ICP OES) was developed. The on-line pre-concentration was based on the complex formation of the analytes with the ammonium salt of O,O-diethyldithiophosphate (DDTP) and using the Amberlite XAD-4 resin as a solid support in a homemade column. Different conditions of the flow injection system, such as solutions flow rates, nebulizer pressure and eluent concentration were optimized. Three certified reference materials of lobster hepatopancreas, dogfish liver and fish protein, three samples of fish muscle and three samples of shrimp were digested with HNO3, H2O2 and H2SO4 in a microwave system under reflux. DDTP was added in the solutions obtained, and the mixture was injected in the FI system. Calibration curves for Cd and Pb were obtained using the standard solutions in the concentration range 0.05-0.5 µg mL-1 in the digestion medium, submitted to the same pre-concentration procedure. The quantification limits (3.3 x LOD) for 5 min of pre-concentration time were 0.005 mg kg-1 Cd2+ and 0.1 mg kg-1 Pb2+ in the sample of fish or shrimp in natura, considering 1.0 g of the sample in a final volume of 50 mL. The agreement of the obtained concentrations with the certified ones (Student t-test, 95% confidence) and the recoveries of spiked real samples, from 90 to 120%, demonstrated good accuracy. Precision was also adequate, with relative standard deviations from 2 to 13%. The method was accurate, precise and certainly could be applied to the digested samples of different natures.

O biomonitoramento de elementos químicos é de extrema importância na avaliação da saúde humana. Entretanto, as concentrações dos elementos químicos nos fluidos biológicos são afetadas por parâmetros ambientais e fisiológicos e, consequentemente, consideráveis variações podem ocorrer entre subgrupos de populações específicas. O Brasil é um país com ampla diversidade ambiental e existe limitado conhecimento de valores de referência para elementos químicos em fluidos biológicos. A espectrometria de absorção atômica (AAS) e a espectrometria de emissão ótica com plasma acoplado indutivamente (ICP-OES) ainda são as técnicas analíticas mais comumente empregadas no biomonitoramento de elementos químicos em amostras clínicas. Entretanto, o uso da espectrometria de massas com plasma acoplado indutivamente (ICP-MS) está se tornando a cada dia mais comum nos laboratórios clínicos. Neste estudo, foi avaliado um método rápido envolvendo simples diluição da amostra para determinação de Al, Ba, Be, Cd, Co, Cu, Cs, Mn, Ni, Pb, Pt, Sb, Se, Sn, Tl e U em urina por ICP-MS. Amostras de urina (500 μL) foram pipetadas em frascos cônicos de 15 mL e diluídas para 10 mL com uma solução contendo 0,5 % (v/v) HNO3 + 0,005% (v/v) Triton X-100. Ródio, irídio e ítrio foram adicionados como padrões internos. Em seguida, as amostras foram diretamente analisadas por ICP-MS com calibração por ajuste de matriz. Os limites de detecção do método (3s, n = 20) foram da ordem de ng L-1 para todos os analitos em estudo. O método foi aplicado para a análise de 412 amostras de urina de brasileiros saudáveis e não expostos ambientalmente ou ocupacionalmente a metais para o estabelecimento de valores de referência na população brasileira. A validação dos resultados foi acompanhada pela análise de material de referência certificada de urina (SRM) 2670a proveniente do National Institute of Standards and Technology (NIST) e de materiais de referência provenientes do Institut National de Sante' Publique Du Quebec, no Canadá.

Biomonitoring of trace elements is of critical importance in human health assessment. However, trace element concentrations in biological fluids are affected by environmental and physiological parameters, and therefore considerable variations can occur between specific population subgroups. Brazil is a large country with large environmental diversity and with a limited knowledge of the reference values (baseline data) for trace elements in biological fluids. Atomic absorption spectrometry (AAS) and inductively coupled plasma emission spectrometry (ICP-OES) are still the dominant analytical techniques used for biomonitoring trace element analysis in clinical specimens. However, the use of ICP-MS is becoming more usual in clinical laboratory analysis. Then, we evaluated here a simple dilute-and-shoot method for sequential determination of Al, Ba, Be, Cd, Co, Cu, Cs, Mn, Ni, Pb, Pt, Sb, Se, Sn, Tl and U in urine by quadrupole inductively coupled plasma mass spectrometry (q-ICP-MS). Urine samples (500 µL) were accurately pipetted into conical tubes (15 mL) and diluted to 10 mL with a solution containing 0.5 % (v/v) HNO3 + 0.005% (v/v) Triton X-100. Diluted urine samples also contain rhodium, iridium and yttrium added as internal standards. After that, samples were directly analyzed by ICP-MS against matrix-matching calibration. Method detection limit (3s, n = 20) were in the ng L-1 range for all analytes. The method was applied to the analysis of 412 ordinary urine samples from Brazilian healthy and non-exposed subjects to establish reference values. Data validation was provided by the analysis of the standard reference material (SRM) 2670a toxic elements in urine (freeze-dried) (high and low levels) from the National Institute of Standards and Technology (NIST) and reference urine samples from the trace elements intercomparison program operated by the Institut National de Sante' Publique du Quebec, Canada.

Um método para determinação de Na e K em biodiesel proveniente de diferentes óleos vegetais é proposto. São combinadas as vantagens da FAES com a simplicidade da preparação da amostra por microemulsão e calibração usando padrões aquosos. As microemulsões foram preparadas pela mistura de biodiesel, n-propanol e solução aquosa ácida, permitindo o uso de padrões inorgânicos para a calibração. Foram comparadas a introdução discreta (DA) e aspiração contínua (CA) da amostra apresentando LODs semelhantes, na ordem de 0,1 µg g-1 para ambos analitos, que são adequados para a determinação dos mesmos, conforme os limites estabelecidos na legislação brasileira. A exatidão do método foi avaliada por testes de recuperação, com resultados entre 83% e 120% e, por meio da comparação dos resultados obtidos por ICP OES.

A method for the determination of Na and K in biodiesel, from different vegetable oils, is proposed. The advantages of the FAES were combined with the simplicity of microemulsion preparation and calibration using aqueous standards. Microemulsions were prepared by mixing biodiesel samples with n-propanol and aqueous acid solution, which allowed the use of inorganic aqueous standards for the calibration. Sample introduction through discrete aspiration (DA) or by continuous aspiration (CA) were compared, presenting similar LODs, in the order of 0.1 µg g-1 for both analytes, adequate to the established limits in the Brazilian legislation. The accuracy of the method was checked through recovery tests, with results between 83% and 120%, and through the comparison of the results with those obtained by ICP OES.