Paulo Tiglea

Sulfonamidas em leite por cromatografia líquida de alta eficiência com derivação pré-coluna e detecção por fluorescência

O objetivo deste trabalho foi avaliar e validar um metodo para deteminacao de residuos de sulfatiazol (STZ), sulfametazina (SMZ) e sulfadimetoxina (SDM) em leite UHT integral. A extracao foi realizada com diclorometano e coluna de extracao em fase solida de silica. Os residuos, apos derivacao com fluorescamina, foram quantificados por cromatografia liquida de alta eficiencia com detector de fluorescencia. O limite de deteccao das tres sulfas em amostra de leite integral foi 0,3 µg L-1 e o limite de quantificacao foi 1 µg L-1 para STZ e SMZ e 2,5 µg L-1 para SDM, com coeficientes de variacao entre 4,4 e 6,6%. Os valores de recuperacao para STZ, SMZ e SDM foram 63,2, 91,2 e 63,2%, respectivamente. Considerando o limite maximo de residuo estabelecido pela legislacao brasileira de 100 µg kg-1 para a soma das concentracoes totais de STZ, SMZ e SDM, o metodo descrito permite a determinacao simultânea dos tres analitos em amostras de leite UTH integral.

Total Arsenic, Cadmium, and Lead Determination in Brazilian Rice Samples Using ICP-MS

This study is aimed at investigating a suitable method for rice sample preparation as well as validating and applying the method for monitoring the concentration of total arsenic, cadmium, and lead in rice by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Various rice sample preparation procedures were evaluated. The analytical method was validated by measuring several parameters including limit of detection (LOD), limit of quantification (LOQ), linearity, relative bias, and repeatability. Regarding the sample preparation, recoveries of spiked samples were within the acceptable range from 89.3 to 98.2% for muffle furnace, 94.2 to 103.3% for heating block, 81.0 to 115.0% for hot plate, and 92.8 to 108.2% for microwave. Validation parameters showed that the method fits for its purpose, being the total arsenic, cadmium, and lead within the Brazilian Legislation limits. The method was applied for analyzing 37 rice samples (including polished, brown, and parboiled), consumed by the Brazilian population. The total arsenic, cadmium, and lead contents were lower than the established legislative values, except for total arsenic in one brown rice sample. This study indicated the need to establish monitoring programs for emphasizing the study on this type of cereal, aiming at promoting the Public Health.

Comparação de diferentes métodos estatísticos utilizados para avaliar o desempenho de participantes em um programa de ensaio de proficiência

Five statistical approaches were applied for assessing the performance of participants in 19 rounds (2007-2011) of the Proficiency Testing Program for lead in blood determination (PEP-Pbs), conducted by Instituto Adolfo Lutz. The performance evaluation was provided by using the z-score. The following statistical approaches were tested: 1 – mean and standard deviation, after rejecting outliers; 2 – median and normalized inter-quartile range; 3 – robust mean and robust standard deviation; 4 – robust mean and standard deviation for proficiency assessment of 3 μg/100 mL (for concentrations up to 40 μg/100 mL and a standard deviation for proficiency assessment of 7.5 % of the assigned value (for concentrations above 40 μg/100 mL); 5 – robust mean and standard deviation for proficiency assessment of 2 μg/100 mL (for concentration up to 40 μg/100 mL) or 5 % of the assigned value (for concentrations above 40 μg/100 mL). The approach 4 showed to be the most adequate statistical methodology to assess the performance of participating laboratories in the PEP-Pbs.Five statistical approaches were applied for assessing the performance of participants in 19 rounds (2007-2011) of the Proficiency Testing Program for lead in blood determination (PEP-Pbs), conducted by Instituto Adolfo Lutz. The performance evaluation was provided by using the z-score. The following statistical approaches were tested: 1 – mean and standard deviation, after rejecting outliers; 2 – median and normalized inter-quartile range; 3 – robust mean and robust standard deviation; 4 – robust mean and standard deviation for proficiency assessment of 3 μg/100 mL (for concentrations up to 40 μg/100 mL and a standard deviation for proficiency assessment of 7.5 % of the assigned value (for concentrations above 40 μg/100 mL); 5 – robust mean and standard deviation for proficiency assessment of 2 μg/100 mL (for concentration up to 40 μg/100 mL) or 5 % of the assigned value (for concentrations above 40 μg/100 mL). The approach 4 showed to be the most adequate statistical methodology to assess the performance of participating laboratories in the PEP-Pbs.

Validation of methodology for determining As, Pb and Cd in fish by using ICP-MS: Preliminary studies

The progress of industry has led to the increased emission of pollutants into ecosystems, and fish consumption has been a remarkable source of human exposure to toxic metals. Arsenic, cadmium and lead constitute a potentially significant threat to human health because they are associated with several adverse health effects. Therefore, fish biomonitoring has been a crucial tool for assessing the environmental exposure to contaminants. This study aimed at determining arsenic, cadmium and lead contents in fish samples from a Proficiency Testing for Metals conducted by the Nuclear and Energy Research Institute (IPEN), in order to develop a routine analytical methodology using ICP-MS. The methodology was evaluated by using the certified reference oyster tissue material, which indicated good agreement between the certified and the determined concentrations for As, Cd and Pb. The report on the Proficiency Test performance evaluation, based on the z-score index, evidenced satisfactory results in both samples of the analyzed elements.