In the present study a selective method is presented for the simultaneous determination of copper and cadmium in food samples by adsorptive stripping voltammetry. In preliminary studies, it has been proven that the copper and cadmium react with 3-aminophthalhydrazide (luminol), giving rise to the formation of these complexes. These complexes have adsorptive characteristics on hanging mercury drop electrode (HMDE) and can be reduced in a reduction step. In this study the optimum reaction parameters and conditions studies are investigated. The calibration graphs were linear in the concentration range of 0.5–105.0 and 0.8–70.0ng/ml for copper and cadmium, respectively. The limit of detection of the method was 0.04ng/ml for Cu²⁺ and 0.02ng/ml for Cd²⁺. The interference of some common ions was studied and it was concluded that application of this method for the determination of copper (II) and cadmium in food and water samples led to satisfactory results.

El azufre es un macroelemento esencial en rumiantes. Niveles elevados de azufre y sulfatos consumidos por rumiantes a través de las plantas, agua y otros alimentos pueden reducir el apetito y la tasa de crecimiento en los animales, afectar la absorción de otros elementos y causar afecciones respiratorias y/o neurológicas. El propósito de este estudio fue medir los niveles de azufre en la dieta, analizando las praderas (3 muestras por predio) y el agua (1 muestra por predio) en 45 predios dedicados a la producción de carne, de las regiones de La Araucanía, Los Ríos y Los Lagos de Chile durante los períodos de primavera 2008 y verano 2009. Adicionalmente, se obtuvieron muestras de gas ruminal de 5 animales por predio, muestreándose un total de 225 animales por período. Posteriormente, se analizaron las diferencias en las concentraciones de azufre en agua y pradera y H2S en gas ruminal de los predios provenientes de las zonas de la costa, depresión intermedia y precordillera. Los resultados obtenidos indican que las concentraciones promedios de azufre en la pradera fueron de 1.482 ± 592 ppm y de 1.472,1 ± 448 ppm en el periodo primavera y verano respectivamente, no evidenciándose diferencias significativas. La concentración de azufre en agua fue de 1,12 ± 0,1 y 1,14 ± 0,09 ppm durante el período de primavera y de verano, respectivamente. Los resultados de los análisis por región y zona geográfica (costa, depresión intermedia y precordillera) no mostraron diferencias significativas. La concentración de H2S en gas ruminal en los animales en estudio fueron de 273,1 ± 187,5 y de 245,4 ± 180 ppm en primavera y en verano, respectivamente. El análisis de correlación entre variables indicó una asociación positiva entre los niveles de azufre en alimento y H2S en gas ruminal para el período de primavera y verano. El consumo promedio total de azufre estimado considerando las fuentes de pradera y agua en 45 predios durante ambos períodos fue < 0,2% de azufre en la dieta. En conclusión, los resultados indican que las concentraciones de azufre encontradas en los predios ganaderos de las regiones de La Araucanía, Los Ríos y Los Lagos de Chile no representan riesgo para el consumo en bovinos. | Sulphur is an essential element for the metabolism of ruminant animals. However, high dietary concentrations of sulphur are potentially harmful. The purpose of this study was to measure the forage and water sulphur content in samples from 45 beef herds from the La Araucanía, Los Ríos y Los Lagos regions of Chile. Additionally, ruminal gas hydrogen sulphide (H2S) concentrations were obtained from 5 animals on each farm. Samples were collected during the spring 2008 and summer 2009. Pasture sulphur content was 1,482 ± 592 ppm in the spring and 1,471 ± 448 ppm in the summer. Water sulphur concentrations in all farms was < 1.5 ppm each season. Ruminal gas H2S concentrations in animals was 273 ± 187.5 ppm and 245.4 ± 173 ppm in spring and summer, respectively. Positive and significant correlations were found between pasture sulphur content and ruminal H2S concentration for both periods. Estimated total sulphur intake considering pastures and water was < 0.2% sulfur on a dry matter basis. The results of this study suggest that forage and water sulphur concentrations in Southern Chile do not represent a potential risk of intoxication in grazing beef cattle.

The following research consisted of 500 broiler chickens were distributed in four treatments with two repetitions, only in the initial stage (0 - 3 weeks). The study was done to determine the effect of lactosuero as a supplement in feeding for broiler chickens, supplied in liquid form, in three concentrations (10%, 15% and 20%). The lactosuero was applied as a supplement in the drinking water, mixing it daily with water treatments (T1: 10%) (T2: 15%) (T3: 20%) in a ratio of (1:9 ie 1 L of lactosuero per 9 L of water) (1.5:8.5 ie 1.5 L of lactosuero per 8.5 L of water) (2:8 or 2 L of lactosuero per 8 L of water). The control treatment was given water and B complex in intensive farming. As for the Power System in the control treatment (T0), food was traditional, that is, with all the inputs required for breeding and in treatments (T1, T2 and T3), the food was not added fishmeal, that provided the lactosuero is supplied with water, the food was given them daily, worth mentioning that the lactosuero that was given to the chickens was fresh, which was collected daily from the company DANE. The parameters evaluated were: water consumption, feed conversion and economic profitability. According the results were determined that the treatments (T1 and T2) had a positive effect of lactosuero as a food supplement, so that is a new alternative for poultry farmers, this input lowers production costs and of course increases the utility. | El presente trabajo consistió en la crianza de 500 pollos parrilleros, distribuidos en cuatro tratamientos con dos repeticiones, solo en la etapa de inicio (0-3 semanas). La investigación se hizo para determinar el efecto del lactosuero como suplemento en la alimentación de los pollos broiler, suministrada en forma líquida, en tres concentraciones. El lactosuero se aplicó como un suplemento en el agua de bebida, mezclando diariamente con el agua de los tratamientos (T1:10%), (T2:15%) y (T3:20%), en una proporción de (1:9 es decir 1 L de lactosuero por cada 9 L de agua) (1.5:8.5 es decir 1.5 L de lactosuero por cada 8.5 L de agua) y (2:8 o es decir 2 L de lactosuero por cada 8 L de agua). El tratamiento testigo se le dio agua más complejo B así como en una crianza intensiva. En cuanto al Sistema de alimentación en el tratamiento testigo (T0), la alimentación fue el tradicional, es decir con todos los insumos requeridos para una crianza, y en los tratamientos (T1, T2 y T3), al alimento no se le agregó la harina de pescado, es decir se le proporcionaba el lactosuero suministrado con agua; el alimento se les proporcionaba de manera diaria, cabe mencionar que el lactosuero que se daba a los pollos era fresca, lo cual se recogía a diario de la empresa DANE. Los parámetros que se evaluaron fueron, el consumo de agua, la conversión alimenticia y la rentabilidad económica. De acuerdo los resultados obtenidos se determinaron que los tratamientos (T1 y T2) obtuvieron un efecto positivo del lactosuero como suplemento alimenticio, de tal manera que es una nueva alternativa para los avicultores ya que este insumo abarata los costos de producción y lógicamente incrementa la utilidad.

The present study aimed: (i) to develop models for the combined effect of water activity (0.99, 0.94 and 0.90), microstructure expressed as 0, 5, 10 and 20% w/v gelatin, and temperature (15, 20 and 25 °C), on growth and OTA production rates by Aspergillus carbonarius; and (ii) to evaluate the performance of the developed models on food matrices (jelly, custard and marmalade) of different viscosity at pH 5.5. The square root of biomass increase rate (fungal growth rate) and OTA production rate were determined by the Baranyi model and were further modeled as a function of temperature, gelatin concentration and aw by applying polynomial models. Time for visible growth and the upper asymptote of the OTA production curve were also determined by the Baranyi model. Increase in gelatin concentration resulted in a significant delay in all parameters describing fungal growth and OTA production rates, at all temperatures and aw. The effect of microstructure on fungal growth and OTA production rates was less evident at stress conditions of aw and temperature. Detection time for visible fungal growth was markedly influenced by aw and temperature. Coefficients of determination were 0.899 and 0.887 for the models predicting the square root (μₘₐₓ) of growth and OTA production rate, respectively. Predictions of growth rate agreed well with the recorded data of custard and marmalade, while observations of OTA production rate indicated low agreement with model predictions, in all food matrices except for marmalade. The present findings may provide a basis for reliable assessment of the risk of fungal growth and OTA production in foods of different structural and rheological properties.

In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0M HNO₃, and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00–120.0μgL⁻¹ for Cu(II). The limit of detection (3σ), limit of quantification (10σ), and enrichment factor are 0.56μgL⁻¹, 2.0μgL⁻¹ and 41, respectively. The relative standard deviation (n=6) at 20μgL⁻¹ of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results.

Some hemipteran xylem and phloem-feeding insects have evolved specialized alimentary structures or filter chambers that rapidly transport water for excretion or osmoregulation. In the whitefly, Bemisia tabaci, mass movement of water through opposing alimentary tract tissues within the filter chamber is likely facilitated by an aquaporin protein. B. tabaci aquaporin-1 (BtAQP1) possesses characteristic aquaporin topology and conserved pore-forming residues found in water-specific aquaporins. As predicted for an integral transmembrane protein, recombinant BtAQP1 expressed in cultured insect cells localized within the plasma membrane. BtAQP1 is primarily expressed in early instar nymphs and adults, where in adults it is localized in the filter chamber and hindgut. Xenopus oocytes expressing BtAQP1 were water permeable and mercury-sensitive, both characteristics of classical water-specific aquaporins. These data support the hypothesis that BtAQP1 is a water transport protein within the specialized filter chamber of the alimentary tract and functions to translocate water across tissues for maintenance of osmotic pressure and/or excretion of excess dietary fluid.

A separation and preconcentration procedure was developed for the determination of trace amounts of Cd(II), Cu(II), Ni(II), and Pb(II) in water and food samples using Amberlite XAD-2 fuctionalized with a new chelating ligand, 3-(2-nitrophenyl)-1H-1,2,4-triazole-5(4H)-thione (Amberlite XAD-2-NPTT). The chelating resin was characterized by Fourier transform infrared spectroscopy (FT-IR) and used as a solid sorbent for enrichment of analytes from samples. The sorbed elements were subsequently eluted with 10 mL of 1.0 M HNO3, and the eluates were analyzed by inductively coupled plasma–atomic emission spectrometry. The influences of the analytical parameters including pH, amount of adsorbent, eluent type and volume, flow rate of the sample solution, volume of the sample solution, and effect of matrix on the preconcentration of metal ions have been studied. The optimum pH for the sorption of four metal ions was about 6.0. The limits of detection were found to be 0.22, 0.18, 0.20, and 0.16 μg L-1 for Cd(II), Cu(II), Ni(II), and Pb(II), respectively, with a preconcentration factor 60. The proposed method was applied successfully for the determination of metal ions in water and food samples.

The study objects were 6 samples of vitamin premixes and 28 samples of food products enriched in vitamins. The methods allow determining the content of vitamins B1, B2, B6, B12, PP, B5, B9, C, B8 in powdery, liquid and solid samples. Sample preparing involved water extraction, filtration, centrifugation. For electrophoresis separation there was used a capillary electrophoresis system Agilent was used with a diode-matrix detector, quartz capillary HPCE stndrd cap Leff/Lgen=475/56 cm. Detection was performed with wavelength of 210, 254, 270 and 292 nm, taking the spectrum 190-400 nm. The optimum conditions for analyzing were experimentally selected. The working buffer having the most effective separating capacity was used (borate buffer in the concentration of 100 mM, pH9.3). The detection limit of vitamins varied from 1.0 to 10.0 mg/kg, the quantitative determination from 4.0 to 30.0 mg/kg. The systematic error was not more than 10%. The results obtained by the developed method and by high effective liquid chromatography highly coincided. The proposed method was characterized by simplicity, high rate and especially suits for determining vitamins in milk and fermented milk products | Объектами исследования служили 6 образцов витаминных премиксов и 28 образцов продуктов питания, обогащенных витаминами. Методика позволяет определять содержание витаминов B1, B2, B6, B12, PP, B5, B9, C, B8 в порошкообразных, жидких или твердых образцах. Пробоподготовка включала экстракцию водой, фильтрование, центрифугирование. Для электрофоретического разделения применяли систему капиллярного электрофореза Agilent с диодно-матричным детектором, кварцевый капилляр HPCE stndrd cap Lэфф/Lобщ=47,5/56 см. Детектирование проводили на волнах длиной 210, 254, 270 и 292 нм, снятие спектра – 190-400 нм. Опытным путем были подобраны оптимальные условия анализа: ввод пробы под давлением 50 мбар в течение 10 с, напряжение (отрицательное): 0 мин – 0 кВ, 60 с – 25 кВ, 90 с – 30 кВ, температура термостата – 25 град. С, продолжительность разделения – 5 мин. Использовался рабочий буфер с наиболее эффективной разделяющей способностью (боратный буфер в концентрации 50 мМ, содержащий натрия додецилсульфат в концентрации 100 мМ, pH 9,3). Предел обнаружения витаминов варьировал от 1,0 до 10,0 мг/кг, количественного определения – от 4,0 до 30,0 мг/кг (для рибофлавина и фолиевой кислоты соответственно). Систематическая ошибка составила не более 10%. Результаты, полученные разработанным методом и методом высокоэффективной жидкостной хроматографии, в высокой степени совпали (коэффициенты корреляции составили 0,9955 для рибофлавина и 0,9985 для пиридоксина гидрохлорида). Предлагаемый метод отличается простотой, высокой скоростью и особенно подходит для определения витаминов в молочных и кисломолочных продуктах