Alternative Ecosorbent for the Determination of Trihalomethanes in Aqueous Samples in SPME Mode.

A new sorbent material based on modified clay with ionic liquid immobilized into an agarose film was developed as part of this study. It was applied to determine organochlorine pollutants, like disinfection byproducts, through headspace solid-phase microextraction-gas chromatography-electron capture detection (HS-SPME-GC-ECD). The disinfection byproducts determined in this study were used as model molecules because they were volatile compounds, with proven severe effects on human health. Their presence in aquatic environments is in trace concentrations (from pg L-1 to mg L-1). They are classified as emergent pollutants and their determination is a challenge for analytical chemists. The parameters which affected the extraction efficiency, i.e., number and distance between SPME discs, salt concentration, the temperature of extraction, extraction time, and desorption time, were optimized. A wide linear dynamic range of 10-1000 ng mL-1 and coefficients of determination better than 0.997 were achieved. The limits of detection and the limits of quantitation were found in the ranges of (1.7-3.7) ng mL-1 and (5.6-9.9) ng mL-1, respectively. The precision, expressed as relative standard deviation (RSD), was better than 8%. The developed sorbent exhibits good adsorption affinity. The applicability of the proposed methodology for the analysis of trihalomethanes in environmental and water samples showed recoveries in the range of 86-95%. Finally, the newly created method fully complied with the principles of green chemistry. Due to the fact that the sorbent holder was made of agarose, which is a wholly biodegradable material, sorbent clay is a widespread material in nature. Moreover, the reagents intercalated into the montmorillonite are new green solvents, and during the whole procedure, low amounts of organic solvents were used.

Desarrollo de un método analítico de preparación de muestras de alimentos para determinar óxidos de colesterol (COP) mediante cromatografía / Development of an analytical method of food samples preparation to determine cholesterol oxides (COP) by chromatography / Desenvolvimento de um método analítico de preparação de amostras de E alimentos para determinar óxidos de colesterol (COP) por meio de cromatografia E

Resumen Las transformaciones surgidas durante los procesos de limpieza de los alimentos grasos para determinar productos de oxidación de colesterol (COP) limitan los resultados reales en un estudio. Por tanto, el objetivo de este estudio fue comparar los COP obtenidos por distintos métodos de extracción: fase sólida (SPE) y cromatografía líquida en fase normal y reversa, comparando sus perfiles de elución. Adicionalmente, se tuvo como objetivo optimizar los procesos de limpieza para reducir las transformaciones de COP. Se usaron muestras de lomo de cerdo crudo, jamón serrano y salmón ahumado. Las transformaciones de COP se determinaron por SPE y GC-FID y se optimizaron los métodos de limpieza con la técnica SPE. Los cartuchos apolares no mostraron transformación de COP durante el tratamiento de muestras y los cambios de pH generaron transformaciones del triol a 6 ceto epóxido. Debido a que la limpieza del cartucho suele ser deficiente y genera coelución de compuestos indeseables (ácidos grasos) implicados en la transformación de epóxidos α y β en triol, estas transformaciones se evitaron con la técnica SPE, uso de cartuchos C18, con ajuste del volumen de elución de MeOH y ajustes del pH. La reducción de los pasos de la limpieza de muestras optimizó el proceso en un 73%.

Abstract When determining cholesterol oxidation products (COP), transformations during cleaning processes of fatty foods limit the real results in a study. Therefore, the objective of this study was to compare the COP obtained by different extraction methods, normal and reverse phase liquid chromatography and solid phase extraction (SPE), as well as their resulting elution profile. Another goal was to optimize the cleaning processes to reduce COP transformations. Samples of raw pork loin, serrano ham and smoked salmon were used. Transformations of COP were determined by SPE and GC-FID and cleaning methods with SPE technique were optimized. The apolar cartridges did not show COP transformation during samples treatment and pH changes generated transformations of triol to 6 keto epoxide. Due to cartridge cleaning is usually deficient and generates coelution of undesirable compounds (fatty acids) involved in the transformation of α and β epoxides in triol, these transformations were avoided with the SPE technique, C18 cartridges, with adjustment of the MeOH elution volume, and pH settings. Reduction of samples cleaning steps optimized the process in 73%.

Resumo As transformações que surgem durante os E processos de limpeza de alimentos gordurosos para determinar os produtos de oxidação do ^ colesterol (COP) limitam os resultados reais de um estudo. Por tanto, o objetivo deste estudo foi comparar os COP obtidos pelos métodos de extração SPE e cromatografia líquida em fase normal e fase reversa, e seus perfiles de eluição. Além de otimizar os processos de limpeza para reduzir as transformações dos COP. Foram utilizadas amostras de lombo de porco cru, presunto serrano e salmão defumado. As transformações dos COP foram determinadas pela SPE e a GC- FID. Foram otimizados os métodos de limpeza com a técnica de SPE. Os cartuchos apolares não mostraram transformação de COP durante o tratamento das amostras; as mudanças de pH geraron transformações do triol a 6 keto epóxido. A limpeza do cartucho geralmente é deficiente e gera coeluição de compostos indesejáveis (ácidos graxos) envolvidos na transformação dos α e β epóxidos no triol. Essas transformações foram evitadas com a técnica de SPE, o uso de cartuchos C18, ajuste do volume de eluição de MeOH e ajuste do pH. A redução das etapas de limpeza das amostras otimizou o processo em 73%.

Determination of free cholesterol oxide products in food samples by gas chromatography and accelerated solvent extraction: influence of electron-beam irradiation on cholesterol oxide formation.

BACKGROUND: The aim of this study was to develop an efficient method for cholesterol oxide product (COP) determination in irradiated and non-irradiated ready-to-eat foods with high water content by gas chromatography-flame ionisation detector after accelerated solvent extraction (ASE), and derivatisation with a silylating reagent. RESULTS: The ASE solvent was an 85:15 v/v petroleum ether/chloroform mixture at 40 °C and 1500 psi followed by solid phase extraction. The ASE method was compared with the established lixiviation method, proving an advantageous alternative which reduces analysis time by a factor of 15 and solvent volume by 50%, and minimises the use of chlorinated solvents. COP derivative structures were identified by gas chromatography coupled with mass spectrometry. Analytical characteristics were determined from standards and recoveries were 63-95%, establishing the validity of the method. CONCLUSION: The results obtained and their analysis by chemometric techniques established COP formation in food samples after e-beam irradiation. Increase in COP concentration depended on both irradiation doses and food composition, mainly water and fat content, although linear correlations among variables were not found. © 2016 Society of Chemical Industry.

Determinación de la formación de óxidos de colesterol en el proceso de preparación de frito pastuso usando como técnica de análisis HPLC / Determination of the formation of cholesterol oxides in the process of preparation of frito pastuso using HPLC as the analysis technique

Introducción: Los procesos de preparación de los alimentos inducen a la formación de compuestos nocivos para la salud, entre estos se encuentran los óxidos de colesterol (COPs). Objetivo: Determinar la formación de 25-hidroxicolesterol (5-colesten-3ß,25-diol), 6-cetocolesterol (3ß-hidroxi-5α-colestan-6-ona) y 7-cetocolesterol (3ß-hidroxi-5α-colestan-7-ona), en el proceso de preparación de frito pastuso (alimento típico de Nariño, Colombia). Materiales y métodos: La determinación de los COPs se realizó mediante extracción en fase sólida (SPE) y cromatografía liquida de alta eficiencia (HPLC-UV) en fase reversa. Los factores evaluados fueron: receta de preparación, tipo de grasa o aceite utilizado y tipo de carne de cerdo, aplicando un diseño experimental DCA con tres factores y tres niveles en cada caso, se realizaron 10 ensayos totalmente aleatorizados por duplicado, para verificar la reproducibilidad de los resultados. El análisis de óxidos de colesterol (COPs) se aplicó a los diferentes insumos para la preparación y en el alimento listo para el consumo. Resultados: El 7-cetocolesterol se determinó en la mayoría de las muestras; los niveles más altos se encontraron en las muestras de los experimentos donde se utilizó: carne de costilla, grasa de cerdo y la receta de fritura directa de la carne. Los niveles más bajos se encontraron para los experimentos donde se utilizó lomo y pierna, aceite reutilizado y preparaciones de la carne a cocción en agua y posterior fritura. Conclusiones: Las desviaciones estándar relativas fueron inferiores al 4,76% obteniendo resultados reproducibles. La identificación de óxidos de colesterol en la presente investigación permitió establecer la influencia que tienen las formas de preparación de los alimentos de consumo frecuente, en la formación de compuestos que presentan reconocidos efectos adversos para la salud humana.

Introduction: Food preparation processes lead to the formation of harmful compounds to health, some of these include oxides of cholesterol (COPs). Objective: To determine the formation of 25-hydroxycholesterol (5-cholesten-3ß, 25-diol), 6-cetocolesterol (3ß-hidroxi-5α-colestan-6-ona) and 7-cetocolesterol (3ß-hidroxi-5α-colestan-7-ona) in the process of preparation of "frito pastuso" (a typical dish in Nariño, Colombia). Materials and methods: The COPs were determined by extraction in solid phase (SPE) and liquid chromatography of high efficiency (HPLC-UV) in reversed phase. The evaluated factors were: recipe, type of grease or oil used and type of pork by using a DCA experimental design with three factors and three levels in each case. 10 totally randomized tests were performed in duplicate to check the reproducibility of the results. The analysis of cholesterol oxides (COPs) was applied to different inputs for the preparation and the food ready for consumption. Results: The 7-cetocolesterol was determined in the majority of samples. The highest levels were found in the samples of the experiments which used rib meat, pork fat and direct meat fried recipe. The lowest levels were found for experiments which used loin and leg, reused oil and the recipe where the meat is first cooked in water before frying. Conclusions: The relative standard deviations were lower to 4,76% where reproducible results were obtained. The identification of cholesterol oxides in this research helped to establish the influence that the different ways to prepare food of frequent consumption have on the formation of compounds that have recognized adverse effects on human health.