RESUMEN
The sonochemical degradation of bisphenol A in aqueous solution, a suspected endocrine disruptor, which can cause several damages for humans, animals and the environment, was investigated at different ultrasonic intensities under air atmosphere. Bisphenol A (0.50mM) was completely degraded after 10, 3 and 2h of ultrasonic irradiation at a frequency of 404kHz, and intensities of 3.5, 9.0 and 12.9kW/m(2), respectively. During ultrasonic irradiation, some aromatic intermediates such as 2-(4-hydroxyphenyl)-2-(3,4-dihydroxyphenyl)propane, commonly known as 3-hydroxybisphenol A were detected. Further cleavage of the aromatic rings resulted in other products, like formaldehyde and organic acids, also being detected. The proposed pathways of bisphenol A degradation by ultrasonic irradiation are based on the above-mentioned intermediates. The relationship between bisphenol A degradation and formation of hydrogen peroxide and nitric acid was taken into account, correlating this to the radicals that take part in the degradation process. In order to optimize the performance of the ultrasonic system, additional experiments using Fenton-like reactions were also carried out. However, the addition of iron (II) sulfate (FeSO(4)) did not increase bisphenol A degradation rates. Compared with the system without iron (II) sulfate, the total organic carbon concentration (TOC) was reduced by about 30%, at 404kHz and 9.0kW/m(2).
Asunto(s)
Fenoles/química , Ultrasonido , Contaminantes Químicos del Agua , Compuestos de BencidriloRESUMEN
Dyestuffs are often present in industrial wastewaters and can consist of hazardous substances which have a serious impact on the environment and personal health. This report describes a system developed to degrade these substances using sonochemical reactions. Ultrasonic frequencies of 118, 224, 404 and 651 kHz and power input values of 11.4, 29.0 and 41.5 W were tested on Rhodamine B and Orange II dyestuff solutions in order to find the best degradation conditions. The ultrasonic irradiation of air-saturated solutions produces free radicals that combine and generates hydrogen peroxide, and compared to the production of hydrogen peroxide when irradiating water, a decrease was found during the irradiation to dyestuff solutions, indicating that some of the free radicals were consumed in the dyestuffs degradation process. The effects of the ultrasonic irradiation conditions on the pH, nitric and nitrous acid formations as well as the total organic carbon value (TOC) were also investigated. For the ultrasonic frequencies of 224, 404 and 651 kHz, the degradation rates were very similar, however, the 118 kHz system presented a degradation rate of about one-third that of the higher frequencies for both dyestuffs. The Rhodamine B solutions were decolorized within 2 h of ultrasonic irradiation for all systems with the exception of the 118 kHz one. For Orange II, except for the 118 kHz system, all solutions were decolorized within 4 h of ultrasonic irradiation. All reactions were carried out at 25 degrees C and the total ultrasonic irradiation time was 10 h.
Asunto(s)
Compuestos Azo/química , Bencenosulfonatos/química , Rodaminas/química , Ultrasonido , Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodos , Carbono/química , Carbono/aislamiento & purificación , Concentración de Iones de Hidrógeno , Ácido Nítrico/química , Ácido Nitroso/química , Compuestos Orgánicos/química , Compuestos Orgánicos/aislamiento & purificación , Factores de TiempoRESUMEN
The conventional treatment of dental caries involves mechanical removal of the affected part and filling of the hole with a resin or metal alloy. But this method is not ideal for tiny early lesions because a disproportionate amount of healthy tooth must be removed to make the alloy or resin stick. Here we describe a dental paste of synthetic enamel that rapidly and seamlessly repairs early caries lesions by nanocrystalline growth, with minimal wastage of the natural enamel.
Asunto(s)
Materiales Biocompatibles/síntesis química , Caries Dental/patología , Esmalte Dental/química , Diente/patología , Materiales Biocompatibles/química , Materiales Biomiméticos/síntesis química , Materiales Biomiméticos/química , Esmalte Dental/ultraestructura , Durapatita/química , Humanos , Microscopía Electrónica de Transmisión , Diente/ultraestructuraRESUMEN
We report a method for determining fluorinated organic compounds such as perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA) and perfluorooctanesulfonylamide (PFOSA) in human blood samples by column-switching liquid chromatography-electrospray mass spectrometry. The sample preparation prior to solid phase extraction (Waters Oasis HLB extraction column) involved simply mixing plasma sample with internal standard followed by centrifugation and extraction. The compounds were separated by reversed-phase chromatography with a C(8) column, and detected by mass spectrometry using selected ion monitoring in the negative mode. The average recoveries of PFOS, PFOA and PFOSA ranged from 82.2 to 98.7% (R.S.D.: from 2.0 to 5.2%, n = 6). The limits of quantitation of PFOS, PFOA and PFOSA at signal to noise (S/N = 10) were 0.5, 0.5 and 1.0 ng ml(-1). The method enables the precise determination of standards and can be applied to the detection of PFOS, PFOA and PFOSA in human plasma samples for monitoring human exposure.
Asunto(s)
Ácidos Alcanesulfónicos/sangre , Caprilatos/sangre , Fluorocarburos/sangre , Sulfonamidas/sangre , Acetatos , Adulto , Cromatografía Liquida , Femenino , Humanos , Indicadores y Reactivos , Masculino , Persona de Mediana Edad , Control de Calidad , Estándares de Referencia , Espectrometría de Masa por Ionización de ElectrosprayRESUMEN
Fluorinated organic compounds (FOCs), such as perfluorooctane sulfonate (PFOS), perfluoro-octanoate (PFOA), and perfluorooctane sulfonylamide (PFOSA), are widely used in the manufacture of plastic, electronics, textile, and construction material in the apparel, leather, and upholstery industries. FOCs have been detected in human blood samples. Studies have indicated that FOCs may be detrimental to rodent development possibly by affecting thyroid hormone levels. In the present study, we determined the concentrations of FOCs in maternal and cord blood samples. Pregnant women 17-37 years of age were enrolled as subjects. FOCs in 15 pairs of maternal and cord blood samples were analyzed by liquid chromatography-electrospray mass spectrometry coupled with online extraction. The limits of quantification of PFOS, PFOA, and PFOSA in human plasma or serum were 0.5, 0.5, and 1.0 ng/mL, respectively. The method enables the precise determination of FOCs and can be applied to the detection of FOCs in human blood samples for monitoring human exposure. PFOS concentrations in maternal samples ranged from 4.9 to 17.6 ng/mL, whereas those in fetal samples ranged from 1.6 to 5.3 ng/mL. In contrast, PFOSA was not detected in fetal or maternal samples, whereas PFOA was detected only in maternal samples (range, < 0.5 to 2.3 ng/mL, 4 of 15). Our results revealed a high correlation between PFOS concentrations in maternal and cord blood (r2 = 0.876). However, we did not find any significant correlations between PFOS concentration in maternal and cord blood samples and age bracket, birth weight, or levels of thyroid-stimulating hormone or free thyroxine. Our study revealed that human fetuses in Japan may be exposed to relatively high levels of FOCs. Further investigation is required to determine the postnatal effects of fetal exposure to FOCs. Key words: cord blood, fluorinated organic compounds, human, PFOA, PFOS, PFOSA, pregnancy.
Asunto(s)
Ácidos Alcanesulfónicos/sangre , Exposición a Riesgos Ambientales , Sangre Fetal/química , Fluorocarburos/sangre , Intercambio Materno-Fetal , Adolescente , Adulto , Factores de Edad , Peso al Nacer , Cromatografía Liquida , Femenino , Humanos , Recién Nacido , Japón , Espectrometría de Masas , EmbarazoRESUMEN
Health Canada reported recently that medical devices containing di(2-ethylhexyl) phthalate (DEHP) should not be used in the clinical treatment of infants, young boys, pregnant women, and nursing mothers. The risk assessment of DEHP released from PVC medical devices is an important issue for hospitalized patients. In this study, a simple, accurate, low-contamination and high-throughput analytical technique for the determination of DEHP in intravenous (IV) solution was developed using column-switching liquid chromatography/mass spectrometry (LC/MS) with an extraction mini-column. The sample preparation for on-line extraction involved simply mixing IV solution with internal standard as DEHP-d(4) in LC glass vials. The IV fat emulsion drug sample cannot be analyzed directly, hence this sample spiked with DEHP-d(4) solution was extracted by hexane and measured by column-switching LC/MS yielding an average recovery of 92.2% (C.V.=7.8%, n=5). A linear response was found for a variety of drugs tested within the validated range of 0.1 or 0.5-10 microg/ml with correlation coefficients (r) greater than 0.99. These results suggest that this method can assay background exposure to DEHP released from PVC medical devices in the patients. The method was applied to various IV solution samples to establish the first screening method for DEHP released from medical devices with respect to their safety.
Asunto(s)
Dietilhexil Ftalato/análisis , Dietilhexil Ftalato/farmacocinética , Cloruro de Polivinilo/análisis , Cloruro de Polivinilo/farmacocinética , Cromatografía Líquida de Alta Presión/métodos , Equipos y Suministros/normas , Infusiones Intravenosas , Soluciones Farmacéuticas/análisis , Soluciones Farmacéuticas/farmacocinética , Espectrometría de Masa por Ionización de Electrospray/métodosRESUMEN
A novel method based on column-switching high-performance liquid chromatography-electrospray mass spectrometry (LC-MS) coupled with an on-line extraction column containing conjugated avidin has been developed for direct injection analysis of di(2-ethylhexyl) phthalate (DEHP) and its metabolite, mono(2-ethylhexyl) phthalate (MEHP), in blood samples. The sample preparation for on-line extraction involved the mixing of blood samples with internal standards, DEHP-d(4) and MEHP-d(4), in LC glass vials. A linear response was found for column-switching LC-MS when tests were conducted within the validated range of 25 to 1000 ng mL(-1) for DEHP and 5 to 1000 ng mL(-1) for MEHP, with correlation coefficients (r) greater than 0.999. In addition, the recoveries of DEHP and MEHP from human plasma were calculated by using this method with on-line extraction, yielding recoveries of up to 91.2% (RSD<5%). We measured the background levels of DEHP and MEHP in six human plasma samples from healthy volunteers and three fetal bovine serum samples for cell-line culture. DEHP and MEHP were not detected in all human plasma samples (N.D. is <25 ng mL(-1) for DEHP, and N.D. is <5.0 ng mL(-1) for MEHP). In contrast, high DEHP contamination of commercially available fetal bovine serum samples was found by this method.