Luzia Shundo

Aflatoxin M1 in milk by immunoaffinity column cleanup with TLC/HPLC determination

During 2002 and 2003, a total of 107 samples of raw, pasteurized and ultrahigh treated temperature (UHT) milk commercialized in the cities of Sao Paulo and Marilia (SP) were analyzed for the presence of aflatoxin M1 (AFM1). AFM1 was detected in 79 (73.8%) of milk samples, ranging from <0.02 to 0.26 mg/L.The samples were analyzed using an immunoaffinity column for cleanup and a thin layer chromatography for determining AFM1. The parameters, such as recovery, repeatibility, detection and quantification limit were evaluated to optimize this method (in-house). Based on spiked samples, the recovery values ranged from 85.83 to 73.86% at levels of 0.010-0.50 mg/L, respectively, and the relative standard deviation for repeatibility ranged from 7.73 to 2.08%. The quantification limit was 0.02 mg/L. The results of some samples analyzed by this method demonstrated a satisfatory correlation when compared with High Performance Liquid Chromatography (HPLC). In conclusion, immunoaffinity column cleanup gave excellent results for recovery, sensibility and sample through put. Despite the high rate of occurrence of AFM1 in samples in both cities, the contamination level could not be considered a serious public health hazard, according to Brazilian legislation.

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.

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.

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.