Janete Alaburda

Presença de compostos de nitrogênio em águas de poços

INTRODUCAO: A presenca de compostos de nitrogenio nos seus diferentes estados de oxidacao e indicativo de contaminacao do aquifero e de possiveis condicoes higienico-sanitarias insatisfatorias. O nitrito e o nitrato estao associados a dois efeitos adversos a saude: a inducao a metemoglobinemia e a formacao potencial de nitrosaminas e nitrosamidas carcinogenicas. Assim, foi verificada a contaminacao das aguas subterrâneas por compostos de nitrogenio, atraves da determinacao de nitrogenio amoniacal, nitrogenio albuminoide, nitrito e nitrato, e avaliada a adequacao da legislacao vigente. MATERIAL E METODO: Foram analisadas 607 amostras de aguas de pocos localizadas predominantemente na Regiao Metropolitana da Grande Sao Paulo, atraves de tecnicas espectrofotometricas na regiao do visivel. RESULTADOS: Os resultados analiticos foram avaliados com base nas legislacoes federal e estadual paulista. Das amostras analisadas, 91 (15%) apresentaram teores de pelo menos uma forma do nitrogenio em desacordo com a legislacao estadual e 24 (4,0%) apresentaram teores de nitrato em desacordo com a legislacao federal. CONCLUSAO: Apenas o nitrato apresenta valor maximo permissivel na legislacao federal, enquanto que a estadual contempla os quatro compostos nitrogenados. Com base nos resultados da presenca significativa desses derivados nas amostras analisadas, os quais comprometem a qualidade das aguas e apresentam riscos potenciais a saude humana, sugere-se a sua inclusao na legislacao federal.INTRODUCTION Nitrogen compounds in drinking waters have been related to groundwater contamination and inadequate sanitary conditions. Nitrite and nitrate are etiologic agents of methemoglobinemia. In acid solution, nitrous acid formed from nitrite can react with secondary amines to form carcinogenic nitrosamines. The survey of ammoniacal and albuminoid nitrogen, nitrite and nitrate in groundwater supplies as regards the extent of the contamination they cause and discussion of the drinking water regulation regarding nitrogen compounds. MATERIAL AND METHOD Samples collected predominantly in the Metropolitan Region of S. Paulo City was analysed for nitrogen compounds using colorimetric methods: N-NH3 and N-albuminoid by the Nessler method, nitrite by diazoted sulfanilamide with N-(1-naphthyl)-ethylenediamine, and nitrate by reaction with phenoldisuplhonic acid. RESULTS Federal and S. Paulo State drinking water regulations, respectively, Portaria 36/90 and Decreto n degree 12.486, were applied to interpret the results obtained. Of the 607 samples analysed. 15% of them had at least one of the concentrations of nitrogen compounds exceeding the maximum contaminant level (MCL) of the S. Paulo State Regulation. Otherwise, as regards the Federal Regulation, only 4% of the samples exceeded the MCL requirement for nitrate. CONCLUSION In federal drinking water regulation only MCL for nitrate is reported. Otherwise, S. Paulo State regulation requirements report MCLs for all the compounds that have been analysed in this work. The observed results showed that concentrations of ammonia and albuminoid nitrogen, and nitrite, as well as nitrate, gave rise to water of inadequate quality, further they may have adverse effects on human health. The inclusion of nitrogen compounds other than nitrate in federal regulation is recommended.

Ochratoxin A in brazilian instant coffee

The aim of this study was to determine the ochratoxin A (OTA) contamination of instant coffee samples collected in the market of the city of Sao Paulo, Brazil from August to December, 2004. The EN 14133/2003 method, originally developed to quantify OTA in wine, grape juice and beer samples, was evaluated and approved for analyzing OTA in instant coffee samples. OTA was isolated in an immunoaffinity column and quantified by HPLC with fluorescence detection. The established detection and quantification limits were 0.16 and 0.52 ng/g, respectively. The recoveries from spiked samples were 92.6 ± 1.7, 83.7 ± 0.8, and 91.0 ± 1.2 % at levels of 3.0, 5.0, and 8.0 ng/g, respectively. Of a total of 82 samples analised, 81 (98.8%) contained OTA at levels ranging from 0.17 to 6.29 ng/g. The high frequency of OTA occurrence in the instant coffee samples demonstrates the importance of an effective control of this product by governmental authorities and industries. The rapid methodology for OTA analysis in instant coffee used in this study was defined and validated, permitting it´s use for quality control of this product.

Ochratoxin A in wines and grape juices commercialized in the city of São Paulo, Brazil

During the summer of 2005, a total of 101 samples of wines and grape juices purchased from supermarkets and retail stores in Sao Paulo city were analysed for the presence of Ochratoxin A (OTA). OTA was evaluated in 29 red wines and 38 grape juices produced in Brazil and in 34 imported red wines (from Argentina, Chile, Uruguay, France, Italy, Portugal, Spain and South Africa). OTA was extracted in an immunoaffinity column and detected by HPLC with fluorescence detection, according to EN 14133/2003. The detection and quantification limits established were 0.01 and 0.03 ng/mL, respectively. The recoveries for wine samples were 94.1, 82.5, 86.1% and the relative standard deviation were 6.10, 1.03, 4.11% at levels of 0.03, 2.0, 5.0 ng/mL, respectively. For grape juice, the recovery was 86.2% and the RSD was 2.01% at a level of 0.4 ng/mL. OTA contamination was found in nine of the 29 Brazilian red wines with levels ranging from 0.10 to 1.33 ng/mL and in 18 of the 34 imported red wines with levels ranging from 0.03 to 0.32 ng/mL. OTA was not detected in any of the grape juice samples analysed. Although the results from the wine samples analysed for the presence of OTA were below to the limits established by EC 123/2005 (2.0 ng/mL), low and continuous exposure to this mycotoxin could be a risk to human health.

Sistematic study of benzo[a]pyrene in coffee samples

A method for extracting and quantifying benzo[a]pyrene (B[a]P) was evaluated and improved for samples of green and roasted ground Arabica (Coffea arabica) and Conillon (Coffea canephora) Brazilian coffees. The influence of the roasting process in B[a]P formation was considered too. These samples were extracted with acetone, followed by saponification and cyclohexane extraction. The extracts were cleaned by chromatography on a silica-gel. The quantification was done by HPLC with reversed-phase and fluorescence detection under isocratic conditions. The detection and quantification limits were 0.03 µg kg-1 and 0.10 µg kg-1, respectively. The recovery ranged from 76 to 116% for concentrations between 1.00 and 3.00 µg kg-1. The values obtained for B[a]P concentrations were from 0.47 to 12.5 µg kg-1 for samples of ground roasted coffee. B[a]P was absent in the green coffee samples. The control of the roasting parameters is fundamental for obtaining a good quality product.

Optimization of the benzo(a)pyrene determination procedure in cachaça.

The present study evaluated and optimized a routine method to quantify and confirm BaP in Brazilian sugar cane spirit (cachaca). Three extraction procedures were tested, one using SPE for extraction and clean-up, while two others were liquid-liquid partition extraction followed by silica gel chromatography clean-up. BaP was quantified by high performance liquid chromatography with fluorescence detection and confirmed by gas chromatography-mass spectrometry. HPLC detection and quantification limits were 0.03 and 0.10 µg L-1, respectively. The recovery results ranged from 82.9 to 97.0% with coefficients of variation (CV) ranging from 0.5 to 4.9% at concentration levels of 0.1, 1.0 and 3.0 µg L-1, which are in accordance with those described by other authors. The three procedures were appropriated to quantify BaP in cachaca, although SPE extraction is the cheapest, fastest and the least solvent-consuming. The levels of BaP contamination on twenty cachaca samples ranged from no detected (LOD < 0.03 µg L-1) to 0.49 µg L-1.

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.

Benzo(a)pireno, carbamato de etila e metanol em cachaças

The objective of this work was to evaluate the presence of benzo(a)pyrene (BaP), ethyl carbamate (EC) and methanol in 61 samples of cachaca. The quantification of BaP was carried out using HPLC with fluorescence detection, EC concentrations was determined by GC/MS and that of methanol, by GC/FID. In all samples, the concentration of methanol remained below 5 mg 100 mL-1 absolute alcohol. The results of BaP varied from <0.03 to 0.86 μg L-1; the values of EC exceeded the limit established by Brazilian legislation (150 μg L-1) in 53% of the samples.

Occurrence of deoxynivalenol in wheat flour, instant noodle and biscuits commercialised in Brazil

ABSTRACT A total of 134 samples, consisting of 58 wheat flour, 40 instant noodle and 36 biscuits, were analysed for the presence of deoxynivalenol (DON). The samples were obtained from retail markets of the city of São Paulo during the period 2010–2014. DON was determined by high performance liquid chromatography with ultraviolet detection and immunoaffinity sample clean-up. Method validation followed international guidelines. The LOD and LOQ were 60 and 200 µg kg−1, respectively, considering the three different types of samples analysed. The lowest recovery found in this study was 91.8% with RSD 4.5% for instant noodles. DON was detected in 91.4%, 97.5% and 97.2% of samples wheat flour, instant noodles and biscuits, respectively, resulting in a total of 94.8% with levels ranging from LOD to 1720.0 µg kg−1.