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au:RICHTER, PABLO

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DETERMINATION OF IBUPROFEN AND 1-HYDROXYIBUPROFEN IN AQUEOUS SAMPLES USING CORK AS A NATURAL PHASE IN ROTATING-DISK SORPTIVE EXTRACTION
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Rojas-Candia, Valentina

; Arismendi, Daniel

; Richter, Pablo

Journal of the Chilean Chemical Society

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nov 2022, Volume 67 N. 4 Pages 5722 - 5726

Abstract: En | Text: En | PDF: En

ABSTRACT Ibuprofen is one of the most widely used nonsteroidal anti-inflammatory drugs due to its analgesic, anti-inflammatory and antipyretic properties, as well as its low cost and easy accessibility. A fraction of the compound and its metabolites are excreted in the urine, being eliminated in the wastewater reaching river waters in the range of ng L-1 to μg L-1. In this context, highly sensitive and selective analytical methods are required to quantify them, including these methods a pre-concentration step. In this work, the use of a microextraction technology based on rotating-disk sorptive extraction, involving a sorptive phase of laminar cork, was implemented for the extraction of ibuprofen and 1-hydroxyibuprofen from aqueous samples and their subsequent determination by gas chromatography coupled to mass spectrometry. The optimal conditions for determination of the analytes were: 20 mL of sample volume, pH 2, 20 % w/v NaCl (to increase the ionic strength), 90 min of extraction time and 2000 rpm of rotation velocity of the disk. Recoveries of 118 and 39 % and relative standard deviations of 6 and 13 % for ibuprofen and 1-hydroxyibuprofen were obtained, respectively. The presence of both compounds in river waters (Mapocho river, Santiago of Chile) at a concentration of 2.56 to 4.08 μg L-1 were found. The use of laminar cork as a natural sorbent phase immobilized in the rotating-disk allowed to extract the analytes from water samples through its lipophilic-hydrophilic balance that favors the interaction with the compounds under study.

Consenso chileno de diagnóstico y manejo de neoplasias quísticas pancreáticas. Club de páncreas Chile-SCHGE
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Espino, Alberto

; Vargas, José Ignacio

; Mancilla, Carla

; Muñoz, Pablo

; Martínez, Waldo

; Menéndez, Alejandra

; Jara, Daniela

; Mansilla, Rodrigo

; Schiappacasse, Giancarlo

; Santamarina, Mario

; Huete, Álvaro

; Candia, Roberto

; Silva, Felipe

; Castillo, Cecilia

; Richter, Hugo

; Mejía, Ricardo

; Vial, Paula

; Robles, Ignacio

; Martínez, Jorge

; Jarufe, Nicolás

; Briceño, Eduardo

; Lembach, Hanns

; Zoroquiain, Pablo

; Roa, Juan Carlos

; Walker, Kenneth

; Torres, Javiera

; Carreño, Laura

; Castiblanco, Adriana

; Fernández, Wanda

; Ríos, Álvaro

; Chandia, Javiera

; Ayala, María José

; Rojas, Tamara

; Verdugo, Jorge

; Berger, Zoltán

Revista médica de Chile

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dec 2021, Volume 149 N. 12 Pages 1773 - 1786

Abstract: En Es | Text: En Es | PDF: En | PDF: Es

Pancreatic cystic neoplasms (PCN) are frequently detected on abdominal images performed for non-pancreatic indications. Their prevalence in asymptomatic population ranges from 2.7 to 24.8%, and increases with age. There are several types of pancreatic cysts. Some may contain cancer or have malignant potential, such as mucinous cystic neoplasms, including mucinous cystadenoma (MCN) and intraductal papillary mucinous neoplasms (IPMN). In contrast, others are benign, such as serous cystadenoma (SCA). However, even those cysts with malignant potential rarely progress to cancer. Currently, the only treatment for pancreatic cysts is surgery, which is associated with high morbidity and occasional mortality. The Board of the Chilean Pancreas Club of the Chilean Gastroenterology Society developed the first Chilean multidisciplinary consensus for diagnosis, management, and surveillance of PCN. Thirty experts were invited and answered 21 statements with five possible alternatives: 1) fully agree; 2) partially agree; 3) undecided; 4) disagree and 5) strongly disagree. A consensus was adopted when at least 80% of the sum of the answers “fully agree” and “partially agree” was reached. The consensus was approved by the Board of Directors of the Chilean Pancreas Club for publication.

https://doi.org/10.4067/s0034-98872021001201773 73 downloads

FIRST- DERIVATIVE SPECTROFLUORIMETRIC DETERMINATION OF ENROFLOXACIN AND CIPROFLOXACIN IN COW MILK USING ROTATING SORPTIVE EXTRACTION
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Arriagada M., Gabriela

; Pino, Diego

; Richter, Pablo

; Toral, Inés M.

Journal of the Chilean Chemical Society

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jan 2021, Volume 66 N. 1 Pages 5035 - 5040

Abstract: En | Text: En | PDF: En

ABSTRACT A derivative spectrofluorimetric method for simultaneous determination of enrofloxacin (EFX) and ciprofloxacin (CFX) in cow milk was developed. The sample preparation was based on rotating disk sorptive extraction (RDSE) using Oasis HLB® as extraction phase and followed by desorption of the analytes with methanol. The final extracts were evaluated by derivative spectrofluorimetry. An analyte-free cow milk was used as blank sample which was spiked with a known amount of analytes for the study of variables. The sample was treated with trichloroacetic acid in order to precipitate proteins. Furthermore, the extraction was carried out in the presence of Mc Ilvaine-EDTA 0.3M buffer to avoid any type of interference from the calcium ion. The variables involved in the RDSE process were pH and extraction time. Spectral variables were also optimized and analytical signals were evaluated at 417nm and 438nm for EFX and CFX, respectively. The limit of detection (LOD) and limit of quantification (LOQ) were 2.98 – 9.04 μg · L−1 and 2.56 – 7.75 μg · L−1, for EFX and CFX respectively. The precision levels, expressed as relative standard deviation, for EFX and CFX were 3.2% and 3.0%, respectively. The recoveries were between 98.8% to 100.5%. Commercial milks were analyzed and both antibiotics shown concentrations below to LOD in the batches analyzed. Finally, the proposed method offers advantages in terms of simplicity, efficiency and cost. Besides being friendly with the environment.

169 downloads

Partitioning of the water soluble versus insoluble fraction of trace elements in the city of Santiago, Chile
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Rubio, María A.

; Sánchez, Karen

; Richter, Pablo

; Pey, Jorge

; Gramsch, Ernesto

Atmósfera

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2018, Volume 31 N. 4 Pages 373 - 387

Abstract: En Es | Text: En Es | PDF: En | PDF: Es

ABSTRACT The total elemental composition and the water-soluble fraction of PM10 from three different urban areas in Santiago, Chile, from downtown to the suburbs, were investigated. PM10 samples collected during the month of May (mid-autumn in the Southern Hemisphere) in 2006, 2008, 2009, and 2010 were analyzed for major and trace metals, and the partitioning between the insoluble and soluble fractions was determined for most of them. PM10 average concentrations ranged from 71 µg m-3 (Cerrillos) to 128 µg m-3 (La Pintana), which are within the seasonal ranges observed in Santiago. Twenty five major and trace elements (Fe, Al, Ca, K, Mg, P, Pb, S, Ti, Mn, Cu, Zn, Ba, Zr, Cr, As, Sn, Sb, Ni, V, Li, Co, Cd, La, and Rb) were determined in the present study. Ba, Sb, Cd, As, and Zn, with proportions in the soluble fraction varying from 50% to 98%, were the most soluble elements. On the contrary, the less soluble trace elements were Ti, Sn, Pb, and Cr. Most of the high-solubility trace metals are strongly linked to non-exhaust traffic emissions, as well as to certain industrial sources. Our results evidence the significant amount of soluble trace elements in Santiago’s urban atmosphere classified as toxic and/or carcinogenic, thus suggesting a non-negligible health impact.

RESUMEN Se investigó la composición elemental total y la fracción soluble en agua de PM10 en tres áreas urbanas diferentes de Santiago de Chile, del centro a los suburbios. Las muestras de PM10 recogidas durante el mes de mayo (mediados del otoño en el hemisferio sur) en 2006, 2008, 2009 y 2010 fueron analizadas para metales mayores y trazas, y la partición entre fracciones insolubles y solubles se determinó para la mayoría de ellos. Las concentraciones medias de PM10 variaron de 71 µg m-3 (Cerrillos) a 128 µg m-3 (La Pintana), valores que se encuentran dentro de los rangos estacionales observados en Santiago. Se cuantificaron 25 elementos principales y trazas (Fe, Al, Ca, K, Mg, P, Pb, S, Ti, Mn, Cu, Zn, Ba, Zr, Cr, As, Sn, Sb, Ni, V, Li Co, Cd, La y Rb) en el presente estudio. Ba, Sb, Cd, As y Zn fueron los elementos más solubles, con proporciones que varían de 50% a 98% de solubilidad. Por el contrario, los oligoelementos menos solubles fueron Ti, Sn, Pb y Cr. La mayor parte de los metales traza de alta solubilidad no están solamente fuertemente ligados a la emisión de tubos de escape vehiculares, sino a emisiones vehiculares como el sistema de frenos o a ciertas fuentes industriales. Nuestros resultados evidencian la cantidad significativa de oligoelementos solubles en la atmósfera urbana de Santiago clasificados como tóxicos y/o carcinógenos, lo que sugiere un impacto no despreciable en la salud.

https://doi.org/10.20937/atm.2018.31.04.05 384 downloads

DETERMINATION OF TRICLABENDAZOLE IN CATTLE PLASMA AS ITS SULPHOXIDE AND SULPHONE METABOLITES BY ROTATING DISK SORPTIVE EXTRACTION COMBINED WITH HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY AND ITS APPLICATION TO PHARMACOKINETIC STUDIES
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CAÑAS-MÜLLER, ALEJANDRO

; VARGAS DEL CAMPO, MARCIAL

; RICHTER, PABLO

Journal of the Chilean Chemical Society

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dec 2016, Volume 61 N. 4 Pages 3195 - 3200

Abstract: En | Text: En | PDF: En

In this study, a new method for determination of triclabendazole (TCB) as its main metabolites, triclabendazole sulfoxide (TCB-SO) and triclabendazole sulfone (TCB-SO2) in animal plasma was developed. TCB is widely used as antiparasitic in the veterinary industry. Rotating disk sorptive extraction (RDSE) was the selected sample preparation technique for extraction/clean up of the compounds from the samples followed by high performance liquid chromatography coupled to diode array detection (HPLC-DAD) for quantification. Optimization of physicochemical variables was performed using a multivariate experimental design. Following the recommendations given in the Veterinary International Conference on Harmonization guides (VICH GL02 and VICH GL49), the validation of the method was performed, given rise to improved analytical features compared with those provided by other methods based on solid phase extraction (SPE). Linearity (r > 0.99) was achieved for both compounds when calibration was performed not only in standard solutions but also in animal spiked plasma. Selectivity, defined as the response ratio between blank and analyte at the limit of quantification, was 11.8% and 3.4% for TCB-SO and TCB-SO2, respectively. Accuracy and precision, expressed in percentage, were always lower than -16.7% and 8.1%, respectively. Eco-efficiency was quantitatively assessed indicating that the method is an excellent green method. The proposed analytical method was applied to the determination of the pharmacokinetic of two commercial products of TCB in cattle plasma after oral administration. The good analytical performance, eco-efficiency and economy, make the method interesting for alternative use in routine laboratories.

650 downloads

Strategic orientations and cooperation of external agents in the innovation process of rural enterprises
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Reis Neto, José Francisco dos

; Muñoz-Gallego, Pablo Antonio

; Souza, Celso Correia de

; Pedrinho, Denise Renata

; Favero, Silvio

; von Mühlen, Alex Sandro Richter

Ciência Rural

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oct 2016, Volume 46 N. 10 Pages 1878 - 1884

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

RESUMO: Este artigo fornece evidências empíricas sobre as relações entre a orientação para o mercado, a orientação empreendedora e a colaboração dos agentes externos nos processos de inovações incrementais e radicais em empresas rurais. A pesquisa testou três conjuntos de hipóteses: no primeiro, relacionaram-se as contribuições das orientações estratégicas e os processos de inovação; no segundo, verificaram-se as colaborações dos agentes externos na implementação dos processos de inovação e, no terceiro, avaliaram-se os efeitos de moderação do ambiente e da intensidade competitiva no relacionamento entre as orientações estratégicas e os processos de inovações. Os dados foram coletados em 208 empresas rurais e analisados com o emprego de técnicas da modelagem de equações estruturais pelo método de mínimos quadrados parciais. Os resultados mostram que a orientação para o mercado contribui para o desenvolvimento da inovação incremental, e que a orientação empreendedora contribui na implementação das inovações incrementais e radicais. Os agentes específicos (compradores, fornecedores de bens e serviços, consultores e outros agricultores), colaboram positivamente na execução da inovação incremental, mas os agentes genéricos, não. Os agentes genéricos (universidades e organizações públicas) são as que intervêm mais na inovação radical. Destaca-se a utilização de teoria consistente na área de estratégia, marketing e gestão na identificação de que algumas das suas relações causais são confirmadas para as empresas rurais, e outras não, em decorrência da estrutura, do mercado e dos produtos produzidos por elas.

ABSTRACT: This article provides empirical evidence for the relationship between the market orientation, entrepreneurial orientation, and collaboration of external actors in the processes of incremental and radical innovations in rural enterprises. The research tested two sets of assumptions: first, the relation between contributions of strategic orientation and innovation processes; and second, collaborations of external stakeholders in the implementation of innovation processes. Data were collected from 208 rural enterprises and analyzed with the use of techniques of partial least squares structural equation modeling. Results showed that the market orientation contributes to the development of incremental innovation, and that the entrepreneurial orientation contributes to the implementation of the incremental and radical innovations. Specific agents (buyers, suppliers of goods and services, consultants, and others producers), collaborate positively in implementing incremental innovation; however, generic agents do not. The generic agents (universities and specialized public organizations) are the ones that most intervene in radical innovations. The use of consistent theory in the areas of strategy, marketing and management in identifying that some of their causal relationships are confirmed for rural businesses unlike others, due to the structure of the market and the products produced by them.

https://doi.org/10.1590/0103-8478cr20160094 2259 downloads

Evaluación de la calidad de la asistencia en la Unidad Docente Asistencial de Mastología del Hospital de Clínicas
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Camejo, Natalia

; Castillo, Cecilia

; Richter, Lucía

; Artagaveytia, Nora

; Hernández, Ana L.

; Castro, Teresa

; Castillo, Andrea

; Sciuto, Pablo

; Laviña, Guillermo

; Bernachin, Julia

; Milans, Soledad

; Lavista, Fernando

; Vilas, Ana

; Delgado, Lucía

Revista Médica del Uruguay

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sep 2015, Volume 31 N. 3 Pages 165 - 171

Abstract: Es Pt En | Text: Es Pt En | PDF: Es | PDF: Pt | PDF: En

Introducción: el cáncer de mama (CM) es el cáncer más frecuente en la mujer uruguaya, cada año se registran unos 1.840 casos nuevos y unas 660 mujeres mueren como consecuencia de esta enfermedad. Con el fin de mejorar la calidad de la asistencia de las pacientes portadoras de patología mamaria se creó la Unidad Docente Asistencial de Mastología (UDAM) en el año 2009. Objetivo: valorar la calidad de la asistencia en la UDAM del Hospital de Clínicas. Material y método: estudio observacional, retrospectivo, que incluyó a las pacientes diagnosticadas y tratadas por CM en una UDAM desde junio de 2009 hasta junio de 2014. Para valorar la calidad de la asistencia se utilizaron los indicadores propuestos por la Sociedad Europea de Mastología (EUSOMA) en 2010. Resultados: se incluyeron 115 pacientes tratadas por CM; la mediana de edad fue de 63 años, la mayoría de las pacientes tuvieron CM limitados a la mama o axila, receptores hormonales (RRHH) positivos / HER2 negativos. Se cumplieron los criterios de calidad relacionados con el diagnóstico preoperatorio, informe anatomopatológico, tratamiento quirúrgico, radiante y oncológico. Sin embargo, en el 40% de los casos el intervalo de tiempo entre el diagnóstico y el primer tratamiento oncológico fue superior a seis semanas. Conclusiones: la atención recibida por las pacientes asistidas en nuestra UDAM en el período de referencia cumplió con la mayoría de los indicadores propuestos por EUSOMA. Se destaca la necesidad de mejorar el tiempo de espera entre el diagnóstico y el primer tratamiento oncológico.

Resumo Introdução: no Uruguai o câncer de mama (CM) é o tipo mais frequente na mulher; a cada ano aproximadamente 1.840 casos novos são registrados e 660 mulheres morrem como consequência desta patologia. Buscando melhorar a qualidade da assistência prestada às pacientes portadoras desta patologia mamaria, em 2009, foi criada a Unidade Docente Assistencial de Mastologia (UDAM). Objetivo: avaliar a qualidade da assistência na UDAM do Hospital de Clínicas. Material e método: estudo observacional, retrospectivo, incluindo as pacientes diagnosticadas e tratadas por CM na UDAM no período junho de 2009 - junho de 2014. Para avaliar a qualidade da assistência foram utilizados os indicadores propostos em 2010 pela Sociedade Europeia de Mastologia (EUSOMA). Resultados: foram incluídas 115 pacientes tratadas por CM; a mediana de idade foi 63 anos; a maioria das pacientes apresentaram CM limitados a mama ou axila, receptores hormonais (RRHH) positivos / HER2 negativos. Os critérios de qualidade relacionados com diagnóstico pré-operatório, laudo anatomopatológico, tratamento cirúrgico, radiante e oncológico foram observados. No entanto, em 40% dos casos o intervalo de tempo entre o diagnóstico e o primeiro tratamento oncológico foi superior a seis semanas. Conclusões: a atenção recebida pelas pacientes assistidas na UDAM no período de estudo cumpriu com a maioria dos indicadores propostos pela EUSOMA. Destaca-se a necessidade de melhorar o tempo de espera entre o diagnóstico e o primeiro tratamento oncológico.

Abstract Introduction: breast cancer is the most frequent types of cancer in Uruguayan women. Every year there are 1,840 new cases and around 660 women die from this disease. The Mastology Teaching Unit was created in 2009 to improve the quality of assistance in patients with breast cancer. Objective: to evaluate the quality of assistance at the Mastology Teaching Unit of the University Hospital. Method: observational, retrospective study that included women diagnosed and treated for breast cancer in a Mastology Teaching Unit from June 2009 through June, 2014. In order to evaluate the quality of assistance the indicators suggested by the European Society of Mastology in 2010 were used. Results: 115 patients treated for breast cancer were included in the study. Average age was 63 years old, most patients had breast cancer limited in the breast or armpit, (RRHH) positive hormonal receptors, HER2 negative. The quality criteria associated to preoperative diagnosis, pathology analysis, surgical treatment, radiotherapy and oncologic treatment were met. However, in 40% of cases the time interval between diagnosis and the first oncologic treatment was over six weeks. Conclusions: care received by patients seen at the Mastology Unit during the referred period met most indicators suggested by the European Society of Mastology. The need to improve the waiting time between diagnosis and the first oncologic treatment is emphasized.

1676 downloads

EXTRACTION OF POLYCYCLIC AROMATIC HYDROCARBONS FROM WATER SAMPLES INTO A ROTATING-DISK MICROEXTRACTOR AND THE SUBSEQUENT DETERMINATION BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY
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CORROTEA, YANINA

; SÁNCHEZ, KAREN

; RUBIO, M. ANGÉLICA

; RICHTER, PABLO

Journal of the Chilean Chemical Society

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jul 2014, Volume 59 N. 2 Pages 2477 - 2480

Abstract: En | Text: En | PDF: En

The rotating disk sorptive extraction (RDSE) technique was applied in this study to the extraction of 16 polycyclic aromatic hydrocarbons (PAHs) in real water samples. The sorptive and desorptive behavior of the analytes were studied by using a rotating disk coated with polydimethylsiloxane (PDMS) on one of its surfaces. The optimal conditions for extractions of all analytes were: rotational velocity of the disk: 1250 rpm; sample volume: 20 mL; matrix modifier: 20 % MeOH and extraction time: 30 min. A desorption time of 10 min at 1250 rpm was used for the analytes using 5 mL of methanol. PAHs were measured in the extract by gas chromatography coupled to mass spectrometry (GC-MS). Under these conditions, recoveries ranging from 84 to 100 % were obtained in drinking water enriched with the analytes, and the precision, expressed as relative standard deviation, was between 2 and 20%. The detection limit of the method was between 8 and 115 ng L-1 depending on the analyte. The method was applied to the analysis of water samples obtained from a lagoon in Curauma, Chile, obtaining quantitative recoveries.

2219 downloads

Integrated pressurized solvent extraction-cleanup for the rapid determination of polychlorinated biphenyls in meat samples
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Toledo-Neira, Carla

; Enríquez, Pedro

; Richter, Pablo

Journal of the Brazilian Chemical Society

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may 2013, Volume 24 N. 5 Pages 743 - 748

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Um método rápido e eficiente, baseado na integração da extração com solvente sob pressão (PSE) com limpeza através do método sólido de extração (SPE) e sistema de cromatografia gasosa com detector por captura de elétrons (GC-ECD) foi desenvolvido para a determinação de bifenilos policlorados (PCBs). Seis indicadores e doze PCBs semelhantes à dioxina foram selecionados como analitos. Este método baseia-se na integração da extração de solvente e de processos de limpeza no interior de uma célula pressurizada de aço inoxidável. As condições de extração otimizadas foram 6 min de extração, a 70 °C e dois ciclos de extração utilizando hexano/cloreto de metileno (1:1, v/v) como solvente de extração. Sílica gel acidificada com ácido sulfúrico foi utilizada para a limpeza integrada do extrato orgânico. Este método permite uma redução significativa no tempo de processo e o consumo de solvente. Repetibilidade, expressa como o desvio padrão relativo, variou de 3 a 6%, e a recuperação para a concentração de 20 ng g-1 variou entre 71 a 104%. O limite de detecção e quantificação variaram de 0,03 a 0,29 ng g-1 e 0,1 a 0,97 ng g-1, respectivamente. A variação linear foi entre 5 e 100 ng g-1. Finalmente, este novo método foi aplicado em amostras de carne de frango e de porco.

A rapid and efficient method based on the integration of pressurized solvent extraction (PSE) with solid phase extraction (SPE) cleanup and gas chromatography system with electron capture detection (GC-ECD) has been developed for determination of polychlorinated biphenyls (PCBs). Six indicators and twelve dioxin-like PCBs were selected as analytes. This method is based on the integration of solvent extraction and cleanup processes inside a pressurized stainless steel cell. The optimum extraction conditions were 6 min of extraction at 70 °C and two cycles of extraction using hexane/methylene chloride (1:1, v/v) as the extraction solvent. Silica gel acidified with sulfuric acid was used for integrated cleanup of the organic extract. This method allows a significant reduction in extraction time and solvent consumption. Repeatability, expressed as the relative standard deviation, ranged from 3 to 6%, and recoveries for concentration of 20 ng g-1 was ranged between 71 to 104% .The limit of detection and quantification ranged from 0.03 to 0.29 ng g-1 and 0.1 to 0.97 ng g-1 respectively. The linear range was between 5 and 100 ng g-1 . Finally this new method was applied to samples of chicken and pork.

https://doi.org/10.5935/0103-5053.20130095 2204 downloads

10.

Multivariate optimization of pressurized solvent extraction of alkylphenols and alkylphenol ethoxylates from biosolids
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Maricán, Adolfo

; Ahumada, Inés

; Richter, Pablo

Journal of the Brazilian Chemical Society

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feb 2012, Volume 23 N. 2 Pages 267 - 272

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Neste estudo, uma metodologia de extração em solvente pressurizado de alquilfenóis (APs) e alquilfenóis etoxilados (APEOs) a partir de biosólidos foi otimizada utilizando-se um biosólido contendo nativamente estes compostos em um nível de concentração elevada. A otimização da extração foi realizada através de um planejamento experimental de análise multivariada com um planejamento composto central (CCD) produzindo os seguintes valores otimizados: temperatura de 129 ºC, tempo de extração por ciclo de 34 min em dois ciclos e acetona como solvente de extração. Em comparação com a extração Soxhlet, esta metodologia acabou por ser mais eficiente para a extração de APEOs e de eficiência semelhante para a extração de APs. Por outro lado, a metodologia é consideravelmente mais rápida do que a de Soxhlet e usa uma pequena quantidade de solvente de extração. As concentrações de 204 ± 20 e 1053 ± 23 mg kg-1 de nonilfenol e nonilfenol-etoxilato, respectivamente, foram determinadas na amostras de biosólido.

In this study, a methodology for pressurized solvent extraction of alkylphenols (APs) and alkylphenol ethoxylates (APEOs) from biosolids was optimized by utilizing a biosolid natively containing these compounds at a high concentration level. Optimization of the extraction was carried out through a multivariate analysis experimental design with a central composite design (CCD) producing the following optimum values for the variables: temperature of 129 ºC, extraction time per cycle of 34 min in two cycles and acetone as extraction solvent. Upon comparison with Soxhlet extraction, this methodology turned out to be more efficient for the extraction of APEOs and of similar efficiency for APs. On the other hand, the methodology is considerably faster than Soxhlet and uses a smaller amount of extraction solvent. Concentrations of 204 ± 20 and 1053 ± 23 mg kg-1 for nonylphenol and nonylphenol-ethoxylate, respectively, were determined in the biosolid sample assayed.

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11.

SORPTION OF POLYBROMINATED DIPHENYL ETHERS IN BIOSOLID MODEL SAMPLES
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RIVAS, JORGE

; TORAL, M. INÉS

; RICHTER, PABLO

Journal of the Chilean Chemical Society

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2012, Volume 57 N. 2 Pages 1087 - 1090

Abstract: En | Text: En | PDF: En

Biosolid model samples (BMSs) were developed to study the capacity of various matrixes to adsorb polybrominated diphenyl ethers (PBDEs) as a function of their composition. A commercial standard reference samples for biosolids containing a certified amount of PBDEs is currently not available for extraction evaluation. Therefore, this study will allow for the selection of an appropriate concentration of PBDEs to produce a reference material for analytes associated with the matrix. The sorption of PBDEs increased clearly concomitantly with the amount of organic matter present in the model, revealing that organic matter rather than the inorganic fraction is mainly responsible for the analyte-matrix interaction. Hydrophobic interactions are predominant in the retention of PBDEs in the biosolid matrix because more hydrophobic congeners are generally sorbed to a higher extent than those that are less hydrophobic. In order to know the probable PBDE sorption mechanism on the model sample of biosolid, the Gibbs free energies were calculated using the Freundlich model, giving values between -8 and -10 kJ/mol. These results suggest that the sorption mechanism of the PBDEs is through physiosorption. Therefore, the Freundlich model should be satisfactory for describing the analyte behavior.

2005 downloads

12.

FERROSPECTRAL SORBED ON DEAE SEPHADEX A-25 FOR THE SOLID PHASE SPECTROPHOTOMETRIC DETERMINATION OF IRON AND COBALT BY BATCH AND CONTINUOUS FLOW MODES
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TORAL, M. INES

; SANCHEZ, GRISEL

; FERNANDEZ, PRISCILLA

; PIZARRO, PATRICIA

; MONCADA, VIVIANA

; RIVAS, JORGE

; RICHTER, PABLO

Journal of the Chilean Chemical Society

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2011, Volume 56 N. 2 Pages 682 - 687

Abstract: En | Text: En | PDF: En

In this work, Ferrospectral;3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine (FST) sorbed on DEAE Sephadex A-25 is used as solid phase for spectrophotometric determination of iron and cobalt by batch and continuos flow modes. In batch simultaneous determination, the second derivative at 536.0 and 601.4 nm were used for iron and cobalt determination, respectively. In this modality, the detection limits (3 o criterion), for iron and cobalt were 1.3, 9.1, ug L¹ and the determination ranges were: 4.3 to 220 and 30.3 to 800 ug L¹. The method by FIA mode was carried out by stopped flow and then the analytical signal was evaluated by second derivative at 560.9 and 482.3 nm for iron and cobalt determination; respectively. In FIA modality, the detection limits for iron and cobalt were 6.4, 31 ug L¹, and the determination ranges 21 to 200 and 106 to 1000 ug L¹ iron and cobalt, respectively. In both modalities the repeatability for iron and cobalt were < 4 % and the recovery was near to 100%. These methods were applied successfully in drinking water and soil samples.

2026 downloads

13.

Assessment of extractability of Cu, Cr, Ni, Pb and Zn in some chilean biosolid-amended soils by using BCR sequential extraction procedure
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Ahumada, Inés

; Maricán, Adolfo

; Retamal, Mauricio

; Pedraza, Cristina

; Ascar, Loreto

; Carrasco, Adriana

; Richter, Pablo

Journal of the Brazilian Chemical Society

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2010, Volume 21 N. 4 Pages 721 - 730

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

O efeito da aplicação de biossólido na distribuição e extração de Cr, Cu, Ni, Pb e Zn foi avaliado em solos Molisol de uma importante zona destinada à agricultura no Chile central. Massas de 15 e 30 Mg ha-1 de biossólidos foram adicionadas aos solos e os mesmos foram incubados por 60 dias sob condições controladas de umidade e temperatura. Quatro biossólidos domésticos foram obtidos em uma das plantas de tratamento de águas residuárias de Santiago. As extrações sequenciais a partir de amostras de biossólido e solo foram efetuadas de acordo com o procedimento recomendado pelo BCR, que se baseia em quatro extrações para obter uma fração solúvel em ácido (trocável, carbonatos), uma fração reduzível (óxidos de ferro/manganês), uma fração oxidável (matéria orgânica e sulfetos) e uma fração residual. Os metais traço foram determinados por espectrometria de absorção atômica com chama e espectrometria de massa acoplada ao plasma indutivo. Dentre os metais determinados em biossólidos, Zn apresentou a concentração mais alta. A quantidade de metais traço determinada em alguns biossólidos, exceto para Ni, foi abaixo dos limites permitidos pela legislação Chilena para biossólidos. Em geral, desconsiderando-se a fração residual, os metais foram encontrados predominantemente nas frações reduzíveis e oxidáveis. Um planejamento multifatorial foi empregado para avaliar os efeitos da quantidade de biossólido aplicada, do tipo de biossólido e do tempo de incubação. A incorporação do biossólido à razão de 30 Mg ha-1 produziu um aumento na disponibilidade de Zn e Ni em todos os solos e de Cu na maioria deles. Por outro lado, Cr e Pb não variaram significativamente. Em geral, os fatores incubação e tipo de biossólido não apresentaram efeitos pronunciados quando comparados com as condições iniciais.

The effect of biosolid application on the distribution and extractability of Cr, Cu, Ni, Pb, and Zn was assessed in Mollisol soils from an important agricultural zone in central Chile. These were amended with biosolids at the amounts of 15 and 30 Mg ha-1 and incubated for 60 days under controlled conditions of moisture and temperature. Four domestic biosolids were obtained from the monofill at one of the Santiago wastewater treatment plants. Biosolid and soil sequential extraction was performed according to the procedure recommended by BCR, which considers four extractions to obtain an acid-soluble fraction (exchangeable, carbonates), a reducible fraction (iron/manganese oxides), an oxidizable fraction (organic matter and sulfides) and the residual one. Trace metals were determined by flame atomic absorption spectrometry and inductively coupled plasma mass spectrometry. Among the metals determined in biosolids, Zn had the highest concentration. Total trace metal contents found, except for Ni in some biosolids, was below the limits allowed by the Chilean regulation for biosolids. In general, without considering the residual fraction, the metals were found predominantly as reducible and oxidizable fractions. A multifactorial design was applied to assess the effects of biosolid application amounts, biosolid type and incubation time. Biosolid incorporation at the amount of 30 Mg ha-1 produced an increase in Zn and Ni availability in all soils and Cu in most of them, while Cr, and Pb showed no significant variations. In general, the factors incubation and type of biosolid did not show remarkable effects compared with initial conditions.

2531 downloads

14.

PRELIMINARY PHYSICAL CHEMICAL CHARACTERIZATION OF RIVER WATERS AND SEDIMENTS AFFECTED BY COPPER MINING ACTIVITY IN CENTRAL CHILE: APPLICATION OF MULTIVARIATE ANALYSIS
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NARVÁEZ, JESSICA

; RICHTER, PABLO

; TORAL, M. INÉS

Journal of the Chilean Chemical Society

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sep 2007, Volume 52 N. 3 Pages 1261 - 1265

Abstract: En | Text: En | PDF: En

The concentration of trace elements and other analytes of environmental interest was determined in waters and sediments of the Coya and Cachapoal rivers (VI Region, Central Chile), which corresponds to a location highly polluted by copper mining activity. Analysis showed the highest pollution at the sampling station closest to the copper smelter (Caletones), then pollutant concentrations decrease at sites far away from this source. The statistical correlation between the different variables determined in waters and sediments was carried out through a principal components analysis (PCA). It was observed that the parameters fell into three groups: (a) analytes present in waters and sediments which come from the mining wastes (b) analytes of lithoge-nic character present in waters plus alkaline and alkaline earth metals plus organic matter present in sediments and waters, and (c) lithogenic elements present in sediments. On the other hand, by using cluster analysis (CA), it was possible to group the different sampling stations according to their extent of pollution

2902 downloads

15.

Screening method for rapid determination of polychlorinated biphenyls in transformer oil by liquid-liquid extraction and gas chromatography-mass spectrometry
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Toledo, Carla

; Valle, Luis

; Narváez, Jessica

; Richter, Pablo

Journal of the Brazilian Chemical Society

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2007, Volume 18 N. 5 Pages 937 - 942

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Um método simples e rápido foi desenvolvido para análise de bifenis policlorados (PBC) em transformadores a óleo. O método baseia-se na extração líquido-líquido em metanol e subseqüente determinação direta por cromatografia gasosa acoplada a espectrômetro de massa. A polaridade do metanol permite extrair PCBs, junto com uma quantidade mínima de componentes apolares do óleo, evitando assim etapas demoradas na preparação de amostras. Uma vez que o padrão estabelecido internacionalmente para resíduos contento PCBs é 50 mg kg-1, o método determina rapidamente se o transformador a óleo está contaminado com PCBs ou não. Para conseguir as melhores condições de extração, foi realizada uma otimização multivariada, considerando duas variáveis significativas: volume de metanol e tempo de extração. Sob condições ótimas, as recuperações de Aroclor 1256 e Aroclor 1260 estavam entre 80 e 100%, e a precisão, expressa como desvio padrão relativo, entre 2 e 4%. O método foi aplicado em amostras reais poluídas com PCBs.

A rapid and simple method was developed for screening polychlorinated biphenyls in transformer oil. The method is based on liquid-liquid extraction in methanol and subsequent direct gas chromatography-mass spectrometric determination. The extent of methanol polarity allows to extract the PCBs, co-extracting a minimum amount of the apolar oil components, thus avoiding the time-consuming steps involving in sample preparation. Since the regulation established internationally for wastes containing PCBs is 50 mg kg-1, the method rapidly determines whether the transformer oil is PCBs-contaminated or not. In order to reach the best conditions for extraction a multivariate optimization was carried out considering two significant variables: volume of methanol and extraction time. Under optimum conditions, recoveries of Aroclor 1256 and Aroclor 1260 were between 80 and 100%, and precision, expressed as relative standard deviation, was from 2 to 4%. The method was applied to real samples polluted with PCBs.

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