Alessandra Vincenzi Jager

Mineral adsorbents for prevention of mycotoxins in animal feeds

Abstract Mycotoxins are toxic metabolites produced by several fungi species, with the aflatoxins, fumonisins, zearalenone, trichothecenes and ochratoxin A being the most important found in feedstuffs. The economic impact caused by mycotoxins motivated the investigation of detoxification strategies to reduce its bioavailability by enterosorption. Although there are several types of adsorbents, the efficiency of the adsorption depends on the physical and chemical characteristics of both the adsorbent and the mycotoxin. This review describes the most important types of mineral adsorbents [aluminosilicates, HSCAS, bentonites (montmorillonites), zeolites, sepiolite, diatomite and activated carbons] used in feeds, especially for poultry and pigs, and their adsorption mechanisms.

Determinação Simultânea de Cátions por Eletroforese Capilar: Fundamentos e Aplicações

FUNDAMENTS AND APPLICATIONS. In this work, the analysis of cations by capillary electrophoresis is reviewed from the theoretical and practical point of view. Separation mechanisms and detection modes are discussed and illustrated. A thorough compilation of the literature over the last ten years, regarding applications of the technique to the analysis of cations in real matrices, is presented.

Simultaneous analysis of aspartame, cyclamate, saccharin and acesulfame-K by CZE under UV detection

An alternative methodology for simultaneous analysis of aspartame (ASP), cyclamate (CYC), saccharin (SAC) and acesulfame-K (ACE) by capillary zone electrophoresis was developed and validated. Optimum separation conditions were achieved by evaluation of the effective mobility curve followed by background electrolyte (BGE) optimization through a full 32 factorial design. The optimized electrolyte composed of 20.0 mmol L−1 sodium tetraborate, 15.0 mmol L−1 Tris and 7.5 mmol L−1 benzoic acid (pH 9.15) was suitable for simultaneous direct (ASP, ACE and SAC) and indirect (CYC) UV detection at 215 nm. Method performance was evaluated for linearity (r > 0.992), precision (RSD%: <4.0%, ASP; <3.0%, CYC; <4.5%, SAC and <4.5%, ACE), accuracy (mean recovery range: 101.2%, ASP; 102.2%, CYC; 91.9%, SAC and 94.4%, ACE), detection limit (expressed in mg L−1: 6.80, ASP; 12.0, CYC; 0.50, SAC and 3.30, ACE) and quantification limit (expressed in mg L−1: 22.0, ASP; 40.0, CYC; 1.60, SAC and 10.0, ACE). Method applicability was demonstrated by analysis of lemon tea sachet samples containing ASP, CYC, SAC and ACE.

Applications of capillary electrophoresis to the analysis of compounds of clinical, forensic, cosmetological, environmental, nutritional and pharmaceutical importance

Since its inception in the 80s, capillary electrophoresis has matured into a well-established separation technique, actually encompassing a family of electrodriven techniques with distinct separation mechanisms and selectivity, performed in a single capillary column. In this work, the versatility of capillary electrophoresis in handling materials from a diversity of chemical classes and complex sample matrices is illustrated by representative applications in the clinical, forensic, cosmetological, environmental, nutritional and pharmaceutical areas, grouping together our own research interests and results.

Novel approach for the analysis of glycated hemoglobin using capillary isoelectric focusing with chemical mobilization.

In this work, a novel CIEF methodology for the analysis of the glycated hemoglobin, HbA(1c), in dimethylpolysiloxane coated fused-silica capillaries (DB-1, 50 microm I.D., 27 cm, 0.20 microm coating thickness), using a narrow pH ampholyte mixture (4% pH 6-8:pH 3-10, 10:1, v/v) in 0.30% methylcellulose, was developed. In the focusing procedure, a 0.100-mol l(-1) phosphoric acid solution was used as anolyte and a 0.040-mol l(-1) NaOH solution was used as catholyte. During method development, two types of mobilization of the focused hemoglobins were tested: pressure and chemical mobilization. Chemical mobilization performed better, allowing the complete baseline resolution of the hemoglobin of interest, HbA(1c), from its adjacent peak, HbA, in less than 8 min. In the chemical mobilization procedure, the catholyte was replaced by a 0.040-mol l(-1) NaOH solution containing 0.080 mol l(-1) NaCl. The proposed methodology was applied to the analysis of 31 hemolysate samples and validated with respect to the selectivity, inter-assay and intra-assay precision (both migration time and hemoglobin percentage concentration). In addition, HbA(1c) determinations were compared for the CIEF method and a chromatographic standardized procedure using cation-exchanger columns (Variant, Bio-Rad), adopted in a local clinical laboratory, showing excellent correlation (r(2)=0.872, n=31). The slope was found to be statistically equal to one but the intercept differed from zero. Also the Bland-Altman plot indicates bias, implying that the CIEF method yields HbA(1c) concentration higher than the reference method. The separation of the hemoglobins HbA, HbA(2), HbF and HbA(1c) and the variants HbS and HbC was also demonstrated (8 min run). The resolving power of the proposed CIEF method allowed baseline resolution of hemoglobins with a pI difference as small as ca. 0.03, as it is the case for the pairs HbC/HbA(2) and HbA/HbA(1c).

Assessment of multiple mycotoxins in breakfast cereals available in the Portuguese market

Mycotoxins are secondary metabolites of fungi that cause toxic and carcinogenic effects. Human exposure to multiple mycotoxins constitutes an increasing health concern due to potential mycotoxins combined effects. The presence of mycotoxins mixtures in foodstuffs as cereals has been reported over the last years, but few studies are available concerning its occurrence in cereals primarily marketed for children, a particular vulnerable population group. The present study aims to assess the co-occurrence of twenty-one mycotoxins and metabolites present in breakfast cereals primarily marketed for children in Portugal. Results showed that 96% of the analysed breakfast cereal samples were contaminated with several mycotoxins. Twenty-two combinations were identified including two to seven different mycotoxins. Conclusions pointed out an urgent need to review legislative limits in food matrices consumed by children and to perform a more accurate risk assessment of childrens exposure to mycotoxins mixtures in food.

Determination of Urinary Biomarkers for Assessment of Short-Term Human Exposure to Aflatoxins in São Paulo, Brazil

In the present study, a longitudinal assessment was carried out to evaluate the short-term human exposure to aflatoxins in Pirassununga region, São Paulo, Brazil, by determination of urinary aflatoxins by a liquid chromatography coupled to mass sprectrometry (UPLC-MS/MS) method. Sixteen volunteers with ages ranging from 14 to 55 years old were instructed to collect the early morning first urine four times every three months, from June 2011 to March 2012, totaling 64 samples. Aflatoxin M1 (AFM1) was found in 39 samples (61%) at levels ranging from 0.19 to 12.7 pg·mg−1 creatinine (mean: 1.2 ± 2.0 pg·mg−1 creatinine). Residues of aflatoxins B1, B2, G1, G2 and aflatoxicol were not identified in any urine sample. No significant difference was found among the AFM1 mean levels in urine samples collected in the four sampling periods. The levels of AFM1 found in urine samples indicate a low short-term exposure of the population studied to aflatoxins through the diet, although further investigations are needed to assess other long-term biomarkers of exposure to AFB1.

Recent Trends in Microbiological Decontamination of Aflatoxins in Foodstuffs

Nowadays, about 100,000 fungi have already been identified. From these, more than 400 may be considered potentially toxigenic, and about 5% are known to produce toxic com‐ pounds or classes of compounds that cause adverse effects in animals and humans in sever‐ al parts of the world [1]. These compounds, called mycotoxins, are secondary metabolites of low molecular weight produced by mycelia or spores of filamentous fungi [2]. It is suggest‐ ed that mycotoxin production is generally limited to a relatively small number of mold spe‐ cies, and that toxin may be produced by the whole species or just one specific strain [3]. The more complex the synthesis pathway of a mycotoxin, the lesser the number of mold species that produce it.

Assessment of aflatoxin exposure using serum and urinary biomarkers in Sao Paulo, Brazil: A pilot study.

The aim of this study was to evaluate the human exposure of individuals from Pirassununga, Brazil, to dietary aflatoxins B1 (AFB1) and M1 (AFM1) by determination of serum AFB1-lysine and urinary aflatoxin biomarkers (AFM1 and AFB1-N(7)-guanine). The participants were recruited among employees from a Campus of the University of São Paulo, which provided food samples from their homes, as well as serum and urine samples four times every three months, from June 2011 until March 2012. The probable daily intake (PDI) of aflatoxin was estimated by using the results from analysis of food products collected by the time of samples collection, and data from a 24-hour dietary recall questionnaire. Analyses of AFB1 and AFM1 in food samples were conducted by high-performance liquid chromatography with fluorescence detection. Biomarkers in serum and urine were determined by tandem mass spectrometry. AFB1 and AFM1 were detected in 38 samples of cereals (28%, N=136) and 31 milk products (36%, N=86), respectively. AFB1-lysine and AFB1-N(7)-guanine and were not detected in serum or urine samples, respectively. However, AFM1 was found in 74 urine samples (65%), at mean levels in the 4 sampling times ranging from 0.37±0.23 to 1.70±2.88pg/mg creatinine. The mean PDI varied among different sampling times, ranging from 0.09±0.09 to 1.35±5.98ng/kg body weight/day. A modest though significant correlation (r=0.45; p=0.03; N=23) was found for the first time in Brazil between the AFM1 concentration in urine and the PDI for total aflatoxins (AFB1+AFM1) in sampling 1 (June 2011). Urinary AFM1 was confirmed as very sensitive for monitoring the human exposure to dietary aflatoxin. Further studies using serum and urinary biomarkers are needed to estimate the aflatoxin exposure of populations in higher risk areas in Brazil.

Synthesis and purification of the aflatoxin B1-lysine adduct

Abstract This work reports the chemical synthesis of aflatoxin B1 (AFB1)-lysine based on procedures available in the literature, but using lysine without a protection group in the α-amine group. AFB1-exo-8,9-epoxide was obtained by epoxidation of AFB1 with chloroperoxybenzoic acid in dichloromethane and phosphate buffer. Purification and identification of the AFB1-lysine were conducted by liquid chromatography (LC), and its structure was confirmed by LC with mass spectrometer and diode-array detection. The preparation of AFB1-lysine using lysine without a protection group in the α-amine group was completed in 24 h, being a practical modification of available methods that can be reproduced in analytical laboratories.