Isaura Akemi Okada

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.

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.

A rapid method for mercury determination in urine of workers exposed to mercury vapor

ABSTRACT It is shown that the urine from workers exposed to mercury vapor contains practically only inorganic mercury (II), which can be easily determined by flow injection cold vapor atomic absorption spectrometry after adding only HNO3 to the urine at room temperature. If organic mercury is suspected to be present, the sample is treated with KMnO4/H2SO4 at 80°C - 100°C and total mercury is determined. On using HNO3 only, 30 - 40 urine samples/h can be easily processed. The method presents good accuracy, precision and high sensitivity, achieving a limit of detection and a limit of quantification (L.O.Q), respectively, of 0.12 mg/L and 0.4 mg/L Hg (II) in the final dilution, using 1.0 mL urine. Urine reference SRM - NIST as well as samples from workers exposed to mercury vapor were analyzed by the proposed methodology.

The use of regenerated immunoaffinity columns for aflatoxins B1, B2, G1 and G2 in peanut confection

The aim of this study was to investigate the feasibility of using multitime-regenerated immunoaffinity column (IAC) for aflatoxins B1, B2, G1 and G2 in peanut confection. After each use, the IAC was washed immediately with phosphate-buffered saline and stored for >12h prior to reuse. The evaluation procedure consisted of using extracts of naturallycontaminated peanut confection (4 replicates), aflatoxin-free peanut confection (duplicates), and aflatoxin-free peanut confection sample spiked with the 4 aflatoxins (AFT) at 3 levels in 4 replicates. Each day, 18 test extracts were analyzed using 18 designated IACs. After each use, the IACs were regenerated and reused for corresponding test extracts on the following day. This procedure was repeated daily over the course of 9days. Analytical steps included passing the test extracts through the IACs, washing the columns with water, and eluting AFT with methanol. The eluates were diluted with water and were subjected to reversed phase LC separation, post-column photochemical derivatization and fluorescence detection. After eluting AFT, IACs were immediately regenerated by washing with phosphate buffer solution and storing overnight at 8°C for re-use the following day. Results were analyzed using ANOVA and Tukey tests. The numbers of reuse varied for each AF: For AFB1 AFB2, AFG1and AFG2 could be reused for 9, 6, 6 and 0 times, respectively. According to AOAC method performance criteria, recoveries ranging from 70% to 125% are considered acceptable at the spiking levels used in this study.

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.