Gyula Záray

Liquid chromatographic determination of aflatoxins

Abstract The difurancoumarin derivatives known as aflatoxins are highly toxic fungi metabolites belonging to the vast class of mycotoxins, which can contaminate foods and feeds when storage conditions favor fungal growth. Because of potential health hazards for humans, levels of aflatoxins are monitored throughout the world. During the past two decades several chromatographic and other methods were developed for identification and determination of aflatoxins in agricultural and food products. This paper is a review of the overpressured-layer chromatographic (OPLC) and high performance liquid chromatographic methods most often used for the analysis of aflatoxins. However, emphasis is placed on summarizing the OPLC methods developed for determination of aflatoxins in maize, wheat, fish meat, peanut samples, rice and sunflower seeds spiked with aflatoxins B 1 , B 2 , G 1 and G 2 in concentration of 2–10 μg/cm 3 , which were developed in our laboratory. The results of the proposed validation procedure, whose development was based on the guideline of the International Conference on Harmonization (ICH) for pharmaceutical products (1994, Brussels), for the determination of the above-mentioned aflatoxins in wheat samples are also presented.

Leaching of antimony from polyethylene terephthalate (PET) bottles into mineral water.

The Sb leaching from polyethylene terephthalate (PET) package material into 10 different brands of still (non-carbonated) and sparkling (carbonated) Hungarian mineral water purchased in supermarkets was investigated by inductively coupled plasma sector field mass spectrometry (ICP-SF-MS). The Sb concentration measured in PET package materials varied between 210 and 290 mg/kg. Generally, the Sb concentration of still mineral water was lower than that of sparkling in the case of identical storage time. For modelling improper storage conditions, storage time (10-950 days), temperature (22 degrees C-70 degrees C), illumination (dark vs. 23 W daylight lamp for 116 h) as well as bottle volume (0.5, 1.0 and 1.5 L) were taken into consideration. Under certain extreme light and temperature storage conditions, the Sb concentration of some samples exceeded the concentration value of 2 ng/mL. The extent of Sb leaching from the PET recipients of different brands of mineral water can differ by even one order of magnitude in experiments conducted under the same conditions. Thus, the adequate selection of the polymer used for the production of the PET bottle for the solar water disinfection (SODIS) procedure seems to ensure low Sb levels in the water samples.

Comprehensive characterisation of atmospheric aerosols in Budapest, Hungary: physicochemical properties of inorganic species

Abstract As part of an air pollution project in Budapest, aerosol samples were collected by stacked filter units and cascade impactors at an urban background site, two downtown sites, and within a road tunnel in field campaigns conducted in 1996, 1998 and 1999. Some criteria pollutants were also measured at one of the downtown sites. The aerosol samples were analysed by one or more of the following methods: instrumental neutron activation analysis, particle-induced X-ray emission analysis, a light reflection technique, gravimetry, thermal profiling carbon analysis and capillary electrophoresis. The quantities measured or derived include atmospheric concentrations of elements (from Na to U), of particulate matter, of black and elemental carbon, and total carbonaceous fraction, of some ionic species (e.g., nitrate and sulphate) in the fine ( μm equivalent aerodynamic diameter, EAD) or in both coarse (10– 2 μm EAD) and fine size fractions, atmospheric concentrations of NO, NO2, SO2, CO and total suspended particulate matter, and meteorological parameters. The analytical results were used for characterisation of the concentration levels, elemental composition, time trends, enrichment of and relationships among the aerosol species in coarse and fine size fractions, for studying their fine-to-coarse concentration ratios, spatial and temporal variability, for determining detailed elemental mass size distributions, and for examining the extent of chemical mass closure.

Short-time effect of heavy metals upon microbial community activity

Microcalorimetry was applied to assess and compare the toxic effect of heavy metals, such as As, Cu, Cd, Cr, Co, Pb and Zn, on the soil microbial activities and community. About 1.0 g soil spiked 5.0mg glucose and 5.0mg ammonium sulfate, the microbial activities were recorded as power-time curves, and their indices, microbial growth rate constant k, total heat evolution Q(T), metabolic enthalpy Delta H(met) and mass specific heat rate J(Q/S), were calculated. Comparing these thermodynamic parameters associated with growth yield, a general order of toxicity to the soil was found to be Cr>Pb>As>Co>Zn>Cd>Cu. When soil was exposed to heavy metals, the amount of bacteria and fungi decreased with the incubation time, and the bacterial number diminished sharply. It illustrates that fungi are more tolerant, and bacteria-fungi ratio would be altered under metal stress. To determine the status of the glucose consumed, a glucose biosensor with eggshell membrane was used to measure the remaining glucose in soil sample. Results showed that the time at which glucose was consumed completely was agreed with the microcalorimetric time to a large extent, and depended on the toxicity of heavy metals as well.

Recent trends in total reflection X-ray fluorescence spectrometry for biological applications

This review is focused on the application of total reflection X-ray fluorescence (TXRF) spectrometry in the field of biological research. In the last decade, most papers were published by authors who applied laboratory-scale TXRF equipments. The application of synchrotron radiation as excitation source (SR-TXRF) shows a slowly increasing tendency. In the cited papers the micro-, trace and multielement capability of these TXRF techniques was demonstrated in the clinical and medical laboratory practice, as well as in various plant physiological studies. For speciation of elements in biological matrices, the TXRF was used as element specific detector following an off-line separation step (e.g., thin layer chromatography, high performance liquid chromatography), however, these off-line methods are not competitive with the on-line coupled HPLC-inductively coupled plasma mass spectrometry.

Comparative study of elemental mass size distributions in urban atmospheric aerosol

Elemental mass size distributions in aerosols collected at four different urban sites with gradually increasing overall aerosol mass concentration are presented, compared and discussed in the present paper. The aerosol samples were collected with cascade impactor and stacked filter unit samplers, and were analyzed by particle-induced X-ray emission spectrometry and instrumental neutron activation analysis. Typical coarse-mode elements, i.e., Na, Mg, Al, Si, P, Ca, Ti, Fe, Ga, Sr, Zr, Mo and Ba, exhibited unimodal size distributions at all four urban locations studied, and the mass median aerodynamic diameters were increased with aerosol pollution level. Elements typically related to high-temperature or anthropogenic sources, i.e., S, Cl, K, V, Cr, Mn, Ni, Cu, Zn, Ge, As, Se, Br, Rb and Pb, either had a unimodal size distribution with most or their mass in the fine size fraction or clearly showed a bimodal size distribution at the urban background site. However, significant differences between the size distributions of four sampling sites were noted. There was a clear tendency for the accumulation mode to decrease and for the coarse mode to increase with increasing total aerosol mass concentration. A pronounced resuspension of the soil and roadway dust associated with the fine aerosol particles that were deposited on the ground surface previously, and the condensation process of volatile precursor gases on the already existing aerosol particles can explain the observed tendencies. The elemental mass size distributions derived for the polluted urban environments differ from those typically observed for industrial, combustion or automotive sources. A consequence of the diversity in the size distributions on the PM2.5 speciation concept is also presented.

Comparative toxicity of chlorpyrifos and its oxon derivatives to soil microbial activity by combined methods.

The inhibitory effects of the pesticide Chlorpyrifos (CPF) and its oxon derivative (CPO) on soil microbial activity were evaluated through the measurement of metabolic parameters and the microbial urease enzyme. The thermodynamic parameters related to microbial activity were measured and recorded as power-time curves. Microbial growth rate constant k, total heat evolution Q(T), metabolic enthalpy DeltaH(met), mass specific heat rate J(Q/S), microbial biomass C and inhibitory ratio I were calculated. They showed the linear relationship with doses of CPF and CPO. Thereinto, the linear correlations, k versus biomass C and DeltaH(met) versus biomass C, elucidated that k and DeltaH(met) were growth yield dependent. In this work, 20% inhibitory ratio IC(20) was obtained with 9.8 microg g(-1) for CPF and 0.37 microg g(-1) CPO, meaning that the acute toxicity of CPO was 26 times that of CPF, since the CPO had more potent toxicity to living organism due to its active functional group. Comparing the change tendency of DeltaH(met) and other parameter, the values almost kept constant when exposure to CPF (<5.0 microg g(-1)). It illustrates that individual reacted to stress resulted from environment change by shifting resources from other biological activities (such as reproduction or growth) toward survival to some extent. Urease activity responses in relation to the CPF and CPO exposure were observed and consistent with above thermodynamic parameters.

Effect of particle mass size distribution on the deposition of aerosols in the human respiratory system

Elemental mass size distributions were experimentally determined in atmospheric aerosols collected at four different locations in Budapest, Hungary, comprising a urban background site, two downtown sites and a road tunnel. Based on these distributions, deposition fractions for the various elements in the respiratory system were calculated for a healthy Caucasian adult male, female and 5-year-old child under sitting breathing conditions by a stochastic lung deposition model. The highest deposition values were observed in the extrathoracic region regardless of subjects age and gender, and chemical species and size distributions. Deposition in the tracheobronchial tree and acinar region was much smaller than that in the extrathoracic region. Variations in the deposition fractions due to differences in the size distributions were really significant only in the extrathoracic region. Surprisingly, the different size distributions yielded similar depositions in the thoracic region for a given gender as far as the shape of the deposition curve and the total amount are concerned. Regional deposition fractions were compared for the male, female and child, and for various size distributions (sampling location) and elements.

Study on the leaching of phthalates from polyethylene terephthalate bottles into mineral water

Carbonated and non-carbonated mineral water samples bottled in 0.5-L, 1.5-L and 2.0-L polyethylene terephthalate (PET) containers belonging to three different water brands commercialized in Hungary were studied in order to determine their phthalate content by gas chromatography-mass spectrometry. Among the six investigated phthalates, diisobutyl phthalate, di-n-butyl-phthalate, benzyl-butyl phthalate and di(2-ethyl-hexyl) phthalate (DEHP) were determined in non-carbonated samples as follows: <3.0 ng L(-1)-0.2 μg L(-1), <6.6 ng L(-1)-0.8 μg L(-1), <6.0 ng L(-1)-0.1 μg L(-1) and <16.0 ng L(-1)-1.7 μg L(-1), respectively. Any of the above-mentioned phthalate esters could be detected in carbonated mineral water samples. DEHP was the most abundant phthalate in the investigated samples. It could be detected after 44 days of storage at 22 °C and its leaching was the most pronounced when samples were stored over 1200 days. Mineral water purchased in PET bottles of 0.5L had the highest phthalate concentrations compared to those obtained for waters of the identical brand bottled in 1.5-L or 2.0-L PET containers due to the higher surface/volume ratio. No clear trend could be established for phthalate leaching when water samples were kept at higher temperatures (max. 60 °C) showing improper storage conditions. Phthalate determination by pyrolysis-gas chromatography/mass spectrometric measurements in the plastic material as well as in the aqueous phase proved the importance of the quality of PET raw material used for the production of the pre-form (virgin vs. polymer containing recycled PET).

Lead uptake, distribution, and remobilization in cucumber

Abstract Mobility and distribution of lead (Pb) were investigated in cucumber (Cucumis sativus L.) grown in solution culture. Based on the observation that Pb uptake is influenced by the chemical form of iron (Fe) (complexed or ionic) in the solution, Fe distribution was also determined. Iron concentration was even in the stem (separated to internodes) and petioles but slightly increased at the shoot tip while Pb concentration decreased upwards. In the leaves Fe concentration decreased upwards (whereas in the control it increased a little at the youngest leaves) while Pb concentration increased to the largest leaves then decreased towards the shoot tip. It is suggested that the distribution of Pb in cucumber is passive process and it accumulates in the apoplast while Fe distribution is determined by the requirements of synthetic processes in young or photosynthesizing tissues. Lead probably lowers Fe transport into the symplast in the leaves causing slight chlorosis at the youngest leaves. In the plants t...