Sérgio Dovidauskas

Avaliação dos níveis de chumbo e cádmio em leite em decorrência de contaminação ambiental na região do Vale do Paraíba, Sudeste do Brasil

INTRODUCAO: Localizada em Cacapava, SP, Brasil, industria produtora de lingotes de chumbo provocou contaminacao ambiental na regiao do Vale do Paraiba, com chumbo e cadmio. Com o objetivo de avaliar o grau de contaminacao do leite produzido na regiao, devido a possivel ingestao, pelo gado, de gramineas e aguas contaminadas, foram determinados os teores de chumbo e cadmio no leite. MATERIAL E METODO: Foram analisadas 218 amostras de leite in natura e pasteurizado. O cadmio e o chumbo foram determinados por espectrofotometria de absorcao atomica com chama. RESULTADOS E CONCLUSOES: Das amostras analisadas, 43 apresentaram teores de chumbo acima do limite maximo estabelecido pela legislacao brasileira que e 0,05 mg/kg. O valor da mediana encontrada para o chumbo foi 0,04 mg/L. Os niveis de cadmio em todas as amostras foram menores que o limite de quantificacao do metodo que e 0,02 mg/L. Apesar da contaminacao ambiental, os niveis encontrados para o cadmio no leite estao abaixo do limite estabelecido pela legislacao brasileira que e 1,0 mg/kg.

Tuning the reaction products of ruthenium and ciprofloxacin for studies of DNA interactions

This work presents two potential metallo-drugs, the ionic (C17H19FN3O3)3[RuCl6] · 3H2O (1) and the coordination [Ru(C17H17FN3O3)3] · 4H2O (2) compounds, obtained by the combination of ruthenium(III) and ciprofloxacin in different synthetic conditions. The ESI MS spectrum of 1 displayed a main peak at m/z = 994.6, assigned to the gaseous phase adduct (ciprofloxacin)3 · H+, while 2 featured peaks at m/z 1093.3 and 547.1 ascribed to [Ru(C17H17FN3O3)3 · H+–4H2O]+ and [Ru(C17H17FN3O3)3 · 2H+–4H2O]2+. Thermal analysis corroborated the proposed water content for both complexes. Absorption spectra of the compounds in aqueous medium are dominated by ciprofloxacin transitions in the UV region but displayed weak bands in the visible region, assigned to ligand field transitions. The cyclic voltammograms of 2 exhibited a quasi-reversible process ascribed to the Ru(II)/(III) redox pair at −0.25 V (vs. SHE) while 1 displayed this process at −0.11 V, showing that the central ruthenium ion is stabilized in the (III) oxidation state by the coordination to the hard oxygen atoms of ciprofloxacin. The solubility of 1 is pH dependent (as well as free ciprofloxacin) while 2 is fully water soluble and stable under physiological pH for at least 48 h. The compounds are also stable under incubation conditions (stomach pH and 37°C) without significant pH lowering. An interaction study of 2 with ct-DNA showed a value of K b = 2.47 (±0.89) × 104 mol−1 L for the intrinsic binding constant.

Validação e aplicação de metodologia analítica na determinação de nutrientes inorgânicos em arroz polido

A method of partial digestion of raw milled rice (Oryza sativa) was validated for the determination of inorganic nutrients (Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn) by inductively coupled plasma optical emission spectrometry. Based on hydrolysis with HCl, the method is simple and relatively fast, presenting satisfactory characteristics of performance. This method was used in the preparation of 40 raw milled rice samples commercialized in the state of Sao Paulo, Brazil. Emission spectrometry was applied to determine the mean contents and standard deviations of Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn (in mg.100 g -1 rice), which were 4.31 ± 0.44, 0.22 ± 0.10, 0.32 ± 0.08, 58.0 ± 15.0, 26.1 ± 5.7, 1.06 ± 0.26, 1.78 ± 0.55, 92.1 ± 15.2, and 1.24 ± 0.18, respectively. These results were compared with seven food composition tables available in the literature, which revealed discrepancies for Ca, Fe, Na, and K. Our data were also used to estimate the contribution of Ca, Cu, Fe, Mg, Mn, P and Zn contained in daily rice consumption to the Recommended Daily Intake (RDI). It was found that rice contributes significantly to the RDI, especially of Mn, Cu, and Zn, particularly in view of the average daily consumption of rice per person in Brazil.

Avaliação de limite de decisão (CCa) e capacidade de detecção (CCb) a partir de curvas analíticas em análises de águas para substânciascom teores permitidos: uma planilha eletrônica para a interpretaçãode resultados em Laboratórios de Saúde Pública

In this paper the electronic spreadsheets built in Microsoft ExcelR software are presented, and these parameters enable to estimate the decision limit (CCα) and the detection capability (CCβ) at the detection limit and of the maximum permitted value (MVP) regions. The estimates are evaluated from linear and homoscedastic analytical curves obtained in calibration procedures based on ISO standards and IUPAC guidelines. After validating by means of manual data processing, the electronic spreadsheets were used for determining the nitrite in bottled waters (MVP = 0.02 mg/L) and the fluoride contents in public supply waters (compliance interval = 0.6 to 0.8 mg/L). For fluoride analysis there are the minimum required value (0.6 mg/L) and the maximum acceptable value (0.8 mg/L) for its concentration; therefore, the spreadsheet computes the critical concentration at both limits with a probability of a type I error equal to 0.05. On that account, the electronic spreadsheets provide the rapid decision between compliant and non-compliant data in the interpretation of results.

Emprego de planilhas eletrônicas, baseadas nas normas ISO e recomendações IUPAC, em curvas analíticas da análise de água

This paper describes the development and validation of the electronic spreadsheet in Microsoft Excel® software for evaluating the analytical quality of calibration graphs of linear and homoscedastic functions, used in water physical-chemical analysis by UV-Vis spectrophotometry, and obtained according to ISO standards and IUPAC guidelines. By introducing the absorbance data, the spreadsheet shows the calibration (with respective function) and the residues graphs, and also computes the residual standard deviation, angular coefficient standard deviation, interception standard deviation, and coefficient of determination R2. On prediction terms, the spreadsheets calculate (confidence level at 95 %): the prediction interval (showing the respective curve with upper and lower limits), the absorbance critical value, the concentration critical value (xC), the minimum detectable value of concentration (xD) or detection limit, the quantification limit, and the confidence intervals for samples. From the initial spreadsheet, simplifications were introduced and the new spreadsheets were used for analyzing nitrate, nitrite and iron. The effect of the simplifications on the parameters calculation, and the correlations between xC/xD ISO 11843-1,2 parameters and the CCα(decision limit)/CCβ(detection capability) European Commission parameters, were discussed. Keywords. analytical quality control, analytical curves, water analysis, electronic spreadsheets.