RESUMEN
A reversed-phase HPLC optimization strategy is presented for investigating the separation and retention behavior of aflatoxin B1, B2, G1, G2, ochratoxin A and zearalenone, simultaneously. A fractional factorial design (FFD) was used to screen the significance effect of seven independent variables on chromatographic responses. The independent variables used were: (X1) column oven temperature (20-40°C), (X2) flow rate (0.8-1.2 ml/min), (X3) acid concentration in aqueous phase (0-2%), (X4) organic solvent percentage at the beginning (40-50%), and (X5) at the end (50-60%) of the gradient mobile phase, as well as (X6) ratio of methanol/acetonitrile at the beginning (1-4) and (X7) at the end (0-1) of gradient mobile phase. Responses of chromatographic analysis were resolution of mycotoxin peaks and HPLC run time. A central composite design (CCD) using response surface methodology (RSM) was then carried out for optimization of the most significant factors by multiple regression models for response variables. The proposed optimal method using 40°C oven temperature, 1 ml/min flow rate, 0.1% acetic acid concentration in aqueous phase, 41% organic phase (beginning), 60% organic phase (end), 1.92 ratio of methanol to acetonitrile (beginning) and 0.2 ratio (end) for X1-X7, respectively, showed good prediction ability between the experimental data and predictive values throughout the studied parameter space. Finally, the optimized method was validated by measuring the linearity, sensitivity, accuracy and precision parameters, and has been applied successfully to the analysis of spiked cereal samples.
Asunto(s)
Aflatoxinas/análisis , Cromatografía Líquida de Alta Presión/métodos , Contaminación de Alimentos/análisis , Ocratoxinas/análisis , Zearalenona/análisis , Aflatoxina B1/análisis , Aflatoxina B1/toxicidad , Aflatoxinas/toxicidad , Grano Comestible/química , Grano Comestible/microbiología , Microbiología de Alimentos , Inocuidad de los Alimentos , Humanos , Ocratoxinas/toxicidad , Espectrometría de Fluorescencia , Zearalenona/toxicidadRESUMEN
Aflatoxins were surveyed in 256 rice samples taken from retail markets in different provinces of Iran during October 2007 and July 2008. A methanol/water (80 : 20, v/v) mixture and an aflatoxin immunoaffinity column (IAC) were used for extraction and clean-up. Mycotoxins were determined using HPLC with fluorescence detection and post-column derivatization using a photo-ionization cell. Levels of contamination ranged 0.0-5.8 ng g(-1) (mean, 1.4 ng g(-1)) and 0.1-6.3 ng g(-1) (mean, 1.6 ng g(-1)) for AFB1 and total aflatoxins, respectively. AFB1 was detected in almost all samples. Results showed that 55 samples (21.5%) were contaminated with more than 2 µg kg(-1) of AFB1, while seven samples (2.7 %) contained more than 4 µg kg(-1) total aflatoxins. The calculated probable daily intake of AFB1 from rice for Iranians ranged 1.4-5.8 ng AFB1 per kg body weight per day for average consumers and, hence. exceeding the estimated provisional maximum tolerable daily intake.