Determination of Se by inductively coupled plasma mass spectrometry (ICP-MS) can be difficult due to spectral interferences; however, these interferences can be eliminated by using collision-reaction interface (CRI) technology. A simple and fast procedure for determination of total Se concentration in bovine semen by ICP-MS after sample solubilization with diluted formic acid is here proposed. Formic acid caused an increase of up to 50% in selenium net signals and the maximum gain was obtained at 10% v v-1 formic acid solution. The optimized nebulizer gas flow rates were 1.05 and 0.95 L min-1, and radio frequency applied power were 1.3 and 1.4 kW without and with CRI, respectively. Microwave-assisted acid digestion was also implemented in the preparation of semen sample for comparison of results. No statistical differences between these sample preparation strategies at 95% confidence level (t-test) were observed for 76Se+, 77Se+, 78Se+ and 82Se+ without using CRI and 82Se+ with CRI.

Inorganic elements present in pharmaceutical products were determined by inductively coupled plasma-mass spectrometer (ICP-MS), employing microwave acid digestion as a sample preparation method. The most abundant isotopes, 75As+, 65Cu+, 52Cr+, 58Ni+, 208Pb+, and 51V+, were determined in acyclovir ointment and its constituents. Elemental impurities in the pharmaceutical samples were determined using an inductively coupled plasma-universal cell technology-mass spectrometer (ICP-UCT-MS) operated in kinetic energy discrimination (KED) and standard mode. The accuracy of the method was assessed by means of addition and recovery experiments. Except for Cr, spiked recoveries of the elements added to the samples before microwave acid digestion (MW-AD) step were between 95.1 and 126%, and after MW-AD step ranged from 85.6 to 132%. Limits of detection (LOD) obtained by proposed method is in agreement to those required by the U.S. Pharmacopeia Convention (USP), showing that the ICP-MS technique is well suited for quantification of these elements. The LOD's (ng L-1) for 51V+, 52Cr+, 58Ni+, 65Cu+, 75As+ and 208Pb+ in 1% v v-1 HNO3 medium were: 2.2, 81.3, 91.9, 6.9, 0.2 and 3.1, respectively. The concentration of the analytes in these samples presented a wide range, varying from 2.3 ± 0.8 µg kg-1 for As to 3446 ± 47 µg kg-1 for Cr.

O teor de matéria orgânica do solo (MOS) é estimado pelo conteúdo de carbono orgânico do solo (COS) vezes um fator, decorrente do pressuposto de que 58% da MOS é formada por carbono. Amostras de solos apresentando grande variação no teor de COS foram avaliadas no laboratório. O COS foi determinado pelo método de Walkley-Black (WB) e a MOS pela perda de massa por ignição (PMI). A MOS foi positivamente correlacionada com o COS. A relação MOS/COS variou de 1,91 a 5,08. Este resultado mostra que a MOS brasileiros apresentam maior grau de oxidação. Embora a MOS e o COS tenham diminuído a relação MOS/COS aumentou com a profundidade do solo. Este resultado demonstrou que a MOS da subsuperfície contem mais oxigênio e menos carbono que a MOS da superfície do solo. A relação CTC/COS também aumentou com a profundidade, indicando um aumento nos grupos funcionais da MOS por unidade de carbono.

The quantity of soil organic matter (SOM) was estimated through the determination of soil organic carbon (SOC) times a factor, which assumes that 58% of the SOM was formed by carbon. A number of soil samples with wide range of SOC content collected in the state of Paraná, Brazil were evaluated in the laboratory. SOC was measured by Walkley-Black method and the total SOM by loss on ignition. The SOC was positively correlated with SOM. The SOM/SOC ratio varied from 1.91 to 5.08 for the soils. It shows that Brazilian SOM has greater oxidation degree. Although, the SOM and SOC decreased with soil depth the SOM/SOC ratio increased. It showed that SOM in the subsoil contained more oxygen but less carbon than the SOM in the upper soil surface. The CEC/SOC also increased with depth indicating that the functional groups of the SOM increased per unity of carbon.