Development of an Optical Sensor Using a Molecularly Imprinted Polymer as a Selective Extracting Agent for the Direct Quantification of Tartrazine in Real Water Samples.

This study presents a new optical sensor for tartrazine (TAR) quantification developed using a molecularly imprinted polymer (MIP) as the recognition element, with optical fiber serving as the supporting substrate. The fiber surface was functionalized with 3-(trimethoxysilyl)propyl methacrylate (MPS), and the fiber was coated with MIP using the precipitation polymerization method. The analysis of MIP immobilization on the functionalized optical fiber (FF) was conducted through the use of scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Experimental parameters, such as contact time and fiber length, were adjusted in order to obtain the highest sensitive response signal for the functionalized optical fiber (FF-MIP). The fiber sensor, FF-MIP, exhibited a relatively higher response signal for tartrazine compared to other interfering dyes. The rapid and total desorption of the analyte from FF-MIP allowed the immediate reemployment of FF-MIP, which also presented an acceptable repeatability for the reflectance signal. The imprinting factors for the studied dyes were between 0.112 and 0.936 in front of TAR, 1.405, and selectivity factors were between 1.501 and 12.545, confirming the sensor selectivity. The FF-MIP sensor was successfully applied for tartrazine quantification in real water samples, where it yielded satisfactory results comparable to those of the HPLC reference method.

Tailored synthesis of iron oxide nanoparticles for specific applications using a statistical experimental design.

For this work, iron oxide nanoparticles are synthesized by the co-precipitation method with stoichiometric amounts of Fe2+ and Fe3+ salts in a 1:2 ratio in distilled water and the pH is raised by adding an aqueous ammonia solution by controlled dripping. Nanoparticles precipitating after the reaction time are magnetically filtered and stored in ethanol for further analysis. Superparamagnetic Fe3O4 nanoparticles with a slight deviation from the stoichiometry are obtained, with sizes between 7.4 and 12.8 nm and saturation magnetization between 40 and 78 emu/gr. At pH 6, rod-shaped nanoparticles are obtained in addition to spherical ones. With a statistical design, it is shown how the morphological, structural and magnetic properties of the resulting nanoparticles can be manipulated by the synthesis parameters, offering many possibilities to tailor the materials to a wide range of applications.

Highly emissive MAPbBr3perovskite QDs by ligand-assisted reprecipitation: the antisolvent effect.

A systematic study of the synthetic procedure to improve quantum efficiency of luminescent hybrid perovskite QDs through ligand-assisted precipitation method is presented. Particularly, the influence of the dielectric constant and dipole moment of the antisolvent on the reaction time and the photophysical properties of the QDs is highlighted. After evaluating the influence of antisolvents and optimizing experimental parameters such as reaction time and Pb excess of the precursor, colloidal crystalline MAPbBr3QDs with exceptionally high absolute quantum yield up to 97.7% in solution and 69.1% in solid film were obtained. Finally, MAPbBr3QDs precipitated from anisole were processed like UV-curable nanocomposite as efficient down conversion layer resulting in very narrow green emission light-emitting diode.

Surface molecularly imprinted core-shell nanoparticles and reflectance spectroscopy for direct determination of tartrazine in soft drinks.

The present work shows the synergistic application of reflectance spectroscopy and core-shell molecularly imprinted polymer (MIP) for rapid quantification of tartrazine in soft drinks. Studies evaluated the performance of the MIPs synthesized in the presence of silica nanoparticles unfunctionalized and functionalized with [3-(methacryloyloxy)propyl]trimethoxysilane. Although the use of functionalized silica nanoparticles promoted the highest adsorption capability of tartrazine, the material was found to be less selective when it was applied in real samples. Interestingly, the most accurate results were obtained via the application of the MIP synthesized in the presence of unfunctionalized silica nanoparticles (SiO2@MIP). The optimized core-shell MIP was also characterized by Raman spectroscopy and scanning electron microscopy. The use of direct reflectance spectroscopy in the analyte detection strategy after the template extraction from the MIPs resulted in faster and more accurate results than conventional UV-Visible spectroscopy. With regard to the analysis of the soft drink samples, no significant differences were found between the results obtained from the proposed reflectance spectroscopy-based technique and those obtained from the comparative high-performance liquid chromatography technique. Under optimized conditions, this method displayed a linear range of 1.0-12.5 µmol L-1 with LOD and LOQ values of 0.303 and 1.0 µmol L-1, respectively. The selectivity factor (ß) ranged between 1.4 up to 264 showed better recognition of tartrazine in front of other dyes. Based on the results obtained, the proposed method is found to be suitable for rapid determination of tartrazine in food samples with complex matrices without the need of applying tedious sample preparation and cost-demanding instruments.

Plastic optical fibres applied on the photocatalytic degradation of phenol with Ag2MoO4 and ß-Ag2MoO4/Ag3PO4 under visible light.

In this study, plastic optical fibre (POF) was considered as a light-transmitting medium and substrate for use in a photocatalytic environmental purification system, using Ag2MoO4 and ß-Ag2MoO4/Ag3PO4 as photocatalysts. Pure Ag2MoO4 and a ß-Ag2MoO4/Ag3PO4 composite were synthesized using a facile precipitation method. The composition, structures and optical properties of as-prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), field-emission scanning electron microscopy (FESEM), UV/Vis diffuse reflectance spectroscopy (UV/Vis DRS), BET surface area and TGA/DTG. The catalysts were immobilized on POF and on the glass reactor surface and their efficiency in the phenol degradation was evaluated in a batch reactor under visible light. The use of POF offers advantages such as ease of handling and good adherence characteristics to support Ag2MoO4. The photoactivity follows the order ß-Ag2MoO4/Ag3PO4 ≅ Ag2MoO4 > TiO2 P25, for photocatalysts immobilized on the glass reactor surface or in aqueous suspension. The immobilization of Ag2MoO4 on POF revealed that thinner Ag2MoO4 coatings achieved faster pollutant removal rates from solution, and the optimal catalyst deposition is 0.64 mg/cm2, causing maximum the light penetration and electron-hole generation close to the solid-liquid interface.

Medida del colesterol de lipoproteínas de baja densidad utilizando tres metodologías / Measurement of cholesterol low-density lipoprotein using three methodologies / Medida do colesterol de lipoproteínas de baixa densidade utilizando tres metodologias

Tomando en cuenta que aún no existe una metodología estándar de rutina para la determinación del colesterol de lipoproteínas de baja densidad (LDL-c) se decidió evaluar su determinación analítica utilizando tres técnicas: determinación enzimática homogénea, precipitación con sulfato de polivinilo y fórmula de Friedewald. Fueron procesadas 98 muestras de suero a las cuales se les determinó triglicéridos (TG), colesterol total (CT), colesterol de lipoproteínas de alta densidad (HDL-c) y colesterol de lipoproteínas de baja densidad (LDL-c). Los valores promedio de CT fueron 194,46 ± 43,54 mg/dL, HDL-c 51,12 ± 12,36 mg/dL y TG 132,88 ± 76,93 mg/dL. Aun cuando el análisis de regresión mostró una buena correlación entre los valores de LDL-c, los resultados indicaron una diferencia estadísticamente significativa en los mismos cuando los niveles de TG superaron los 200 mg/dL. La misma se observó principalmente entre el método de precipitación y la fórmula de Friedewald, siendo los valores significativamente más bajos en esta última (LDL-c por precipitación: 141,3 ± 26,2 mg/dL; LDL-c por fórmula de Friedewald: 110,1 ± 35,4 mg/dL). De la misma manera se vio afectada la proporción de individuos clasificados según su riesgo coronario. Es necesario comparar las técnicas aplicadas en este estudio con la cuantificación beta para evaluar cuál tiene un mayor nivel de exactitud.

Considering that there is still no standard methodology for routine determination of low density lipoprotein (LDL-c) it was decided to evaluate their analytical determination using three techniques: homogeneous enzymatic determination, polyvinyl sulphate precipitation and Friedewald formula. Ninety-eight serum samples were processed; triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL-c) and LDL-c were determined. Mean total cholesterol was 194.46 ± 43.54 mg/dL, HDL-C was 51.12 ± 12.36 mg/dL and TG was 132.88 ± 76.93 mg/dL. Although regression analysis showed a good correlation between LDL-c, the results showed a statistically significative difference in them when TG levels exceeded 200 mg/dL. It was mainly observed in the precipitation method and the Friedewald formula, the latter values being significantly lower (LDL-C by precipitation: 141.3 ± 26.2 mg/dL, LDL-C by the Friedewald formula: 110, 1 ± 35.4 mg/dL). Moreover, this difference affected the proportion of individuals classified according to their coronary risk. It is necessary to compare the techniques applied in this study with beta quantification to assess which has a higher level of accuracy.

Levando em consideragao que ainda nao existe uma metodologia padrao de rotina para a determinagao do colesterol de lipoproteínas de baixa densidade (LDL-c) se decidiu avaliar sua determinagao analítica utilizando tres técnicas: determinagao enzimática homogénea, precipitagao com sulfato de polivinil e fórmula de Friedewald. Foram processadas 98 amostras de soro as quais lhes foi determinado triglicerídeos (TG), colesterol total (CT), colesterol de lipoproteínas de alta densidade (HDL-c) e colesterol de lipoproteínas de baixa densidade (LDL-c). Os valores médios de CT foram 194,46 ± 43,54 mg/dL, HDL-c 51,12 ± 12,36 mg/dL e TG 132,88 ± 76,93 mg/dL. Inclusive quando a análise de regressao mostrou uma boa correlagao entre os valores de LDL-c, os resultados indicaram uma diferenga estatisticamente significativa nos mesmos quando os niveis de TG superaram os 200 mg/dL. A mesma se observou principalmente entre o método de precipitagao e a fórmula de Friedewald, sendo os valores significativamente mais baixos nesta última (LDL-c por precipitagao: 141,3 ± 26,2 mg/dL; LDL-c por fórmula de Friedewald: 110,1 ± 35,4 mg/dL). Da mesma maneira se viu afetada a proporgao de indivíduos classificados conforme seu risco coronariano. É necessário comparar as técnicas aplicadas neste estudo com a quantificagao beta para avaliar qual é que tem maior nível de exatidao.

Medida del colesterol de lipoproteínas de baja densidad utilizando tres metodologías / Measurement of cholesterol low-density lipoprotein using three methodologies / Medida do colesterol de lipoproteínas de baixa densidade utilizando tres metodologias

Tomando en cuenta que aún no existe una metodología estándar de rutina para la determinación del colesterol de lipoproteínas de baja densidad (LDL-c) se decidió evaluar su determinación analítica utilizando tres técnicas: determinación enzimática homogénea, precipitación con sulfato de polivinilo y fórmula de Friedewald. Fueron procesadas 98 muestras de suero a las cuales se les determinó triglicéridos (TG), colesterol total (CT), colesterol de lipoproteínas de alta densidad (HDL-c) y colesterol de lipoproteínas de baja densidad (LDL-c). Los valores promedio de CT fueron 194,46 ± 43,54 mg/dL, HDL-c 51,12 ± 12,36 mg/dL y TG 132,88 ± 76,93 mg/dL. Aun cuando el análisis de regresión mostró una buena correlación entre los valores de LDL-c, los resultados indicaron una diferencia estadísticamente significativa en los mismos cuando los niveles de TG superaron los 200 mg/dL. La misma se observó principalmente entre el método de precipitación y la fórmula de Friedewald, siendo los valores significativamente más bajos en esta última (LDL-c por precipitación: 141,3 ± 26,2 mg/dL; LDL-c por fórmula de Friedewald: 110,1 ± 35,4 mg/dL). De la misma manera se vio afectada la proporción de individuos clasificados según su riesgo coronario. Es necesario comparar las técnicas aplicadas en este estudio con la cuantificación beta para evaluar cuál tiene un mayor nivel de exactitud.(AU)

Considering that there is still no standard methodology for routine determination of low density lipoprotein (LDL-c) it was decided to evaluate their analytical determination using three techniques: homogeneous enzymatic determination, polyvinyl sulphate precipitation and Friedewald formula. Ninety-eight serum samples were processed; triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL-c) and LDL-c were determined. Mean total cholesterol was 194.46 ± 43.54 mg/dL, HDL-C was 51.12 ± 12.36 mg/dL and TG was 132.88 ± 76.93 mg/dL. Although regression analysis showed a good correlation between LDL-c, the results showed a statistically significative difference in them when TG levels exceeded 200 mg/dL. It was mainly observed in the precipitation method and the Friedewald formula, the latter values being significantly lower (LDL-C by precipitation: 141.3 ± 26.2 mg/dL, LDL-C by the Friedewald formula: 110, 1 ± 35.4 mg/dL). Moreover, this difference affected the proportion of individuals classified according to their coronary risk. It is necessary to compare the techniques applied in this study with beta quantification to assess which has a higher level of accuracy.(AU)

Levando em consideragao que ainda nao existe uma metodologia padrao de rotina para a determinagao do colesterol de lipoproteínas de baixa densidade (LDL-c) se decidiu avaliar sua determinagao analítica utilizando tres técnicas: determinagao enzimática homogénea, precipitagao com sulfato de polivinil e fórmula de Friedewald. Foram processadas 98 amostras de soro as quais lhes foi determinado triglicerídeos (TG), colesterol total (CT), colesterol de lipoproteínas de alta densidade (HDL-c) e colesterol de lipoproteínas de baixa densidade (LDL-c). Os valores médios de CT foram 194,46 ± 43,54 mg/dL, HDL-c 51,12 ± 12,36 mg/dL e TG 132,88 ± 76,93 mg/dL. Inclusive quando a análise de regressao mostrou uma boa correlagao entre os valores de LDL-c, os resultados indicaram uma diferenga estatisticamente significativa nos mesmos quando os niveis de TG superaram os 200 mg/dL. A mesma se observou principalmente entre o método de precipitagao e a fórmula de Friedewald, sendo os valores significativamente mais baixos nesta última (LDL-c por precipitagao: 141,3 ± 26,2 mg/dL; LDL-c por fórmula de Friedewald: 110,1 ± 35,4 mg/dL). Da mesma maneira se viu afetada a proporgao de indivíduos classificados conforme seu risco coronariano. E necessário comparar as técnicas aplicadas neste estudo com a quantificagao beta para avaliar qual é que tem maior nível de exatidao.(AU)

Medida del colesterol de lipoproteínas de baja densidad utilizando tres metodologías / Measurement of cholesterol low-density lipoprotein using three methodologies / Medida do colesterol de lipoproteínas de baixa densidade utilizando tres metodologias

Tomando en cuenta que aún no existe una metodología estándar de rutina para la determinación del colesterol de lipoproteínas de baja densidad (LDL-c) se decidió evaluar su determinación analítica utilizando tres técnicas: determinación enzimática homogénea, precipitación con sulfato de polivinilo y fórmula de Friedewald. Fueron procesadas 98 muestras de suero a las cuales se les determinó triglicéridos (TG), colesterol total (CT), colesterol de lipoproteínas de alta densidad (HDL-c) y colesterol de lipoproteínas de baja densidad (LDL-c). Los valores promedio de CT fueron 194,46 ñ 43,54 mg/dL, HDL-c 51,12 ñ 12,36 mg/dL y TG 132,88 ñ 76,93 mg/dL. Aun cuando el análisis de regresión mostró una buena correlación entre los valores de LDL-c, los resultados indicaron una diferencia estadísticamente significativa en los mismos cuando los niveles de TG superaron los 200 mg/dL. La misma se observó principalmente entre el método de precipitación y la fórmula de Friedewald, siendo los valores significativamente más bajos en esta última (LDL-c por precipitación: 141,3 ñ 26,2 mg/dL; LDL-c por fórmula de Friedewald: 110,1 ñ 35,4 mg/dL). De la misma manera se vio afectada la proporción de individuos clasificados según su riesgo coronario. Es necesario comparar las técnicas aplicadas en este estudio con la cuantificación beta para evaluar cuál tiene un mayor nivel de exactitud.(AU)

Considering that there is still no standard methodology for routine determination of low density lipoprotein (LDL-c) it was decided to evaluate their analytical determination using three techniques: homogeneous enzymatic determination, polyvinyl sulphate precipitation and Friedewald formula. Ninety-eight serum samples were processed; triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL-c) and LDL-c were determined. Mean total cholesterol was 194.46 ñ 43.54 mg/dL, HDL-C was 51.12 ñ 12.36 mg/dL and TG was 132.88 ñ 76.93 mg/dL. Although regression analysis showed a good correlation between LDL-c, the results showed a statistically significative difference in them when TG levels exceeded 200 mg/dL. It was mainly observed in the precipitation method and the Friedewald formula, the latter values being significantly lower (LDL-C by precipitation: 141.3 ñ 26.2 mg/dL, LDL-C by the Friedewald formula: 110, 1 ñ 35.4 mg/dL). Moreover, this difference affected the proportion of individuals classified according to their coronary risk. It is necessary to compare the techniques applied in this study with beta quantification to assess which has a higher level of accuracy.(AU)

Levando em consideragao que ainda nao existe uma metodologia padrao de rotina para a determinagao do colesterol de lipoproteínas de baixa densidade (LDL-c) se decidiu avaliar sua determinagao analítica utilizando tres técnicas: determinagao enzimática homogénea, precipitagao com sulfato de polivinil e fórmula de Friedewald. Foram processadas 98 amostras de soro as quais lhes foi determinado triglicerídeos (TG), colesterol total (CT), colesterol de lipoproteínas de alta densidade (HDL-c) e colesterol de lipoproteínas de baixa densidade (LDL-c). Os valores médios de CT foram 194,46 ñ 43,54 mg/dL, HDL-c 51,12 ñ 12,36 mg/dL e TG 132,88 ñ 76,93 mg/dL. Inclusive quando a análise de regressao mostrou uma boa correlagao entre os valores de LDL-c, os resultados indicaram uma diferenga estatisticamente significativa nos mesmos quando os niveis de TG superaram os 200 mg/dL. A mesma se observou principalmente entre o método de precipitagao e a fórmula de Friedewald, sendo os valores significativamente mais baixos nesta última (LDL-c por precipitagao: 141,3 ñ 26,2 mg/dL; LDL-c por fórmula de Friedewald: 110,1 ñ 35,4 mg/dL). Da mesma maneira se viu afetada a proporgao de indivíduos classificados conforme seu risco coronariano. E necessário comparar as técnicas aplicadas neste estudo com a quantificagao beta para avaliar qual é que tem maior nível de exatidao.(AU)