Edición 4ta. El Crisol

Colegio de Químicos de Puerto Rico EL CRISOL Revista Científica enero-marzo 2013

Edición 4ta / Volumen 001 Revista El Crisol Página 1

Colegio de Químicos de Puerto Rico 52 Calle Hatillo Hato Rey, Puerto Rico 00919

MENSAJE DE LA PRESIDENTA 2012-2013 ....................................................................................................................................2 EDITORIAL ......................................................................................................................................................................................3 CLIMATE CHANGE INDICATORS FOR PUERTO RICO: I- GENERAL TRENDS IN TEMPERATUR: FROM 1900 TO 2010 .....4 THE USE OF SPIDER WEB AS COLLECTION MEDIA TO DETERMINE INDOOR AIR METAL CONTAMINATION ............. 10 CHARACTERIZATION OF NITROPRUSSIDES............................................................................................................................ 15 Los artículos que aparecen en las revistas del CQPR son responsabilidad de sus autores, por lo tanto, el CQPR, la Junta de Gobierno ni sus auspiciadores se hacen responsables de las opiniones o errores que puedan contener dichos artículos. Nuestros lectores pueden remitir sus comentarios o sugerencias por correo electrónico [email protected] o correo postal del CQPR.

EL CRISOL REVISTA CIENTÍFICA

Edición 4TA. VOLUMEN 001/enero –marzo 2013

COLEGIO DE QUÍMICOS DE PUERTO RICO

JUNTA DE GOBIERNO 2012-2013 Comité Ejecutivo: Lcda. Victoria Martínez, Presidenta Dr. Carlos Ruiz Martínez, Presidente Electo Lcda. Elba I. Cora Figueroa, Secretaria Dr. Roberto Aguayo, Tesorero Dra. Agnes Costa, Pasada Presidenta Inmediata Delegados: Dra. Mari Ann Davison, Academia Dr. Carlos Nieves, Academia Lcdo. Rafael Infante, Academia Lcda. Lavina Lebrón, Gobierno I Lcdo. Edgardo Díaz, Gobierno II Lcda. Flor R. Mattos, Sector Privado Lcda. Flor V. Chinea, Industrial Este Lcda. Solmarie Borrero, Industrial Metro Lcdo. Jocelyn Acevedo, Industrial Norte Lcdo. Wanda de Jesús, Industrial Sur Vacante , Industrial Noroeste Vacante , Industrial Oeste

Contenido


MENSAJE DE LA PRESIDENTA 2012-2013 COLEGIO DE QUÍMICOS DE PUERTO RICO

Estimado Lector:

La Revista EL Crisol es la publicación oficial que auspicia el Colegio de Químicos de Puerto Rico (CQPR). La Revista EL Crisol tiene como objetivo difundir temas científicos e investigaciones sobre la química con el fin de lograr mayor comunicación entre los profesionales y la comunidad en general. La necesidad de propagar artículos y trabajos científicos tiene como propósito motivar nuestra comunidad científica en la investigación y contribuir en el interés de nuestros jóvenes por la química. Esta edición será publicada a través de nuestra página de internet para beneficio de la comunidad científica.

La Revista El Crisol, a cargo de nuestro Comité Junta Editora del CQPR y presidido por la Lcda. Rebecca Soler, aspira a servir de portavoz virtual en temas científicos e investigaciones de interés para la comunidad.

Los artículos son responsabilidad de los autores, por lo tanto ni la Junta de Gobierno ni el Comité Junta Editora del CQPR se hacen responsables por las opiniones de los autores y/o errores que puedan tener dichos artículos.

En esta Edición incluye una selección de artículos variados, entre los que podemos mencionar:

CLIMATE CHANGE INDICATORS FOR PUERTO RICO: I- GENERAL TRENDS IN TEMPERATURE: FROM 1900 TO 2010

THE USE OF SPIDER WEB AS COLLECTION MEDIA TO DETERMINE INDOOR AIR METAL CONTAMINATION

CHARACTERIZATION OF NITROPRUSSIDES

Esperamos que usted pueda disfrutar de la lectura de nuestra 4ta edición de la Revista EL Crisol y que en nuestras próximas ediciones podamos contar con sus valiosas aportaciones científicas.



Junta Editora de la Revista El Crisol 2013 Rebecca Soler Héctor Acosta Luz Silva Carlos Vélez Saludos Cordiales a todos nuestros lectores. Es con gran satisfacción que publicamos otro volumen de la revista EL CRISOL del Colegio de Químicos de Puerto Rico. Nuevamente se abre una oportunidad en donde todos nosotros podremos hacer llegar nuestros escritos relacionados a trabajos investigativos científicos y así compartir los hallazgos que se encontraron mediante la publicación electrónica de la revista científica en el portal del Colegio de Químicos de Puerto Rico. En este volumen encontrarás excelentes artículos que la Junta Editora de la Revista logró recopilar con la cooperación de algunos de nuestros colegas. Demostramos nuestro compromiso ante los avances científicos producto de las investigaciones que realizan profesionales en diversos campos de la Química. Esperamos que se animen a colaborar con la Revista EL CRISOL, haciéndonos llegar sus opiniones, artículos de investigación y otros trabajos de acuerdo a las guías establecidas en nuestro Colegio de Químicos de Puerto Rico.

¡Se parte de tu Revista EL CRISOL!

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EDITORA.

EDITORIAL


CLIMATE CHANGE INDICATORS FOR PUERTO RICO: I- GENERAL TRENDS IN TEMPERATURE

FROM 1900 TO 2010

Rafael Infante Méndez Professor of Chemistry Caribbean University 1015 La Ceiba Ave.

Ponce, Puerto Rico 00731 [email protected]

ABSTRACT The variation in average surface temperature from 1900 to 2010 was study for two municipalities of Puerto Rico: Ponce and San Juan. The results show a steady increase in average temperature for the last one hundred and ten years. An average increase of 0.48oC was obtained for Ponce and 1.7oC for San Juan. The increase of temperature, an indicator of climate change, denotes the occurrence of global warning in Puerto Rico; this is consistent with what is observed in other Caribbean nations and other parts of the world. INTRODUCTION The year of 2007 was of particular importance for the science of climate change, with the work done by IPCC1 producing irrefutable evidence of climate change due to human activities, and putting an end to arguments on the scientific credibility surrounding global warming. The fourth IPCC Report reveals consistent trends of how the world’s climate is evolving2 towards increased warming with profound consequences for the global climate and, therefore, for human beings. Caribbean countries are in the tropics, generally between latitudes 11 and 18 degrees north, from Suriname in the south to The Bahamas in the north. The region generally consists of island states, the exceptions being Belize in Central America, and Guyana and Suriname, situated on the South American continent. The topography is generally rugged and mountainous with small areas of flat land in coastal areas. Several islands are volcanic in origin, while others are comprised primarily of coral. The two dozen island nations of the Caribbean, and the 40 million people who live there, are in a state of increased vulnerability to climate change. Higher temperatures, rises in sea level, and increased hurricane intensity threaten lives, property and livelihoods throughout the region. 1 The World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988. It is open to all member states of the UN and WMO. The role of the IPCC is to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options of adaptation and mitigation. 2 The IPCC 4th Assessment Report (AR4) consists of four volumes released in the course of 2007. Compared to the 2001 report, the AR4 pays greater attention to the integration of climate change with sustainable development and the inter-relationships between mitigation and adaptation. Specific attention is given to regional issues, uncertainty & risk, technology, climate change & water. The Report consist of four sections namely: “The Physical Science Basis”, “Impacts, Adaptation and Vulnerability”, “Mitigation of Climate Change”, and a summary report. http://www.ipcc.ch/press/factsheet.htm.



Puerto Rican rainforests, mangroves, and beaches, important to tourists and residents alike, are extremely vulnerable to climate change. Most of the population lives in or near coastal zones, and most economic activity are located there as well, including most hotels, hospitals, and electric power plants. More than half of the population lives in the San Juan metropolitan area, a coastal city that is very close to sea level. A rise of three feet in sea level would flood large parts of the city3. Eleven of the twelve years from 1995 to 2006 ranks among the warmest years in the instrumental record of global surface temperature4 (since 1850). The total temperature increase between 1850–1899 and 2001–2005 reached 0.76°C. The temperature of the world’s oceans has also been rising, and mountain glaciers and snow cover have declined in both hemispheres. All these phenomena contribute to an average global sea level of 1.8 mm per year from 1961 to 2003, and at a faster rate – about 3.1 mm- from 1993 to 2003. The Caribbean region climate is characterized by dry winters and wet summers with the dominant influence of the North Atlantic subtropical high (NAH). Together with a strong inversion, a cool ocean, and reduced atmospheric humidity, the region is generally at its driest during the Northern Hemisphere winter. An analysis of data from the late 1950s to 2000 has shown that the number of very warm days and nights in the Caribbean is increasing dramatically and very cool days and nights are decreasing, while the extreme inter-annual temperature range is also decreasing. The Caribbean Sea has warmed by 1.5ºC over the last century. The maximum number of consecutive dry days is decreasing and the number of heavy rainfall events is increasing. However, there is a trend towards an overall decrease in precipitation, with prolonged dry spells having occurred over the past few decades5. The following article is the first of a series of three and will present temperature variations at two locations in Puerto Rico: San Juan and Ponce. The other two articles will be related to rainfall variation and the comparison of temperature and rainfall data with other Caribbean countries. RESULTS AND DISCUSSION Average daily temperatures were obtained from the National Climatic Data Center of the National Oceanic Atmospheric Administration (NOAA). A summary of the average monthly temperature, average maximum temperature, and average minimum temperature from 1900 to 2010 for Ponce, PR is shown in Table 1. In order to better visualize temperature changes, average monthly temperatures were calculated in forty years period, the results are shown in Table 2. For some year and for some days within a year data was not available but in our professional judgment these omissions will not change the conclusions of this work.

3 THE CARIBBEAN AND CLIMATE CHANGE THE COSTS OF INACTION. Ramón Bueno, Cornelia Herzfeld, Elizabeth A. Stanton and Frank Ackerman. Stockholm Environment Institute—US Center Global Development and Environment Institute, Tufts University. May 2008. 4 The average of near-surface air temperature over land and sea. 5 UNEP (United Nation Environment Programme), 2008. Climate Change in the Caribbean and the Challenge of Adaptation. UNEP Regional Office for Latin America and the Caribbean, Panama City, Panama. Printed in Panama City, in October 2008.


For Ponce, PR the average temperature for a forty year period increased between 0.3oC and 0.8oC for each month between 1900 and 2009, the overall average temperature increase was 0.48oC which is consistent with previous studies and projections. A plot for monthly temperatures vs. year showed positive slopes for each month between 1900 and 2010, an indication of the gradual temperature increase for the last one hundred and ten years. Table 1. Summary Table for Ponce, PR – Latitude: 18.02’; Longitude: 66.2; Altitude: 9 m.

Month Jan Feb March April May June Avg. Temp. oC 24.7 24.6 25.0 25.8 26.8 27.5 Avg. Max. Temp. oC 26.7 26.9 27.1 27.3 28.2 29 Avg. Min. Temp. oC 22.9 22.3 23.4 24.2 24.9 26 Standard Deviation 0.783 0.734 0.767 0.688 0.649 0.590 % RSD 3.17 2.98 3.07 2.67 2.42 1.03 Month July Aug Sept Oct Nov Dec Avg. Temp. oC 27.7 27.8 27.5 27.2 26.3 25.3 Avg. Max. Temp. oC 28.9 28.9 28.8 28.6 27.8 27.1 Avg. Min. Temp. oC 26.0 25.9 25.5 25.4 24.4 22.9 Standard Deviation 0.563 0.630 0.682 0.609 0.657 0.806 % RSD 2.03 2.27 2.48 2.24 2.50 3.19 Table 2. Average monthly 40 years temperatures for Ponce, PR. Year -Jan- -Feb- -Mar- -Apr- -May- -Jun- 1900-1939 24.3 24.3 24.7 25.6 26.6 27.2 1940-1979 24.6 24.6 25.0 25.8 26.8 27.4 1980-2009 25.1 24.9 25.1 26 27 27.8 T, oC 0.80 0.60 0.40 0.40 0.40 0.60 Year -Jul- -Aug- -Sep- -Oct- -Nov- -Dec- 1900-1939 27.6 27.8 27.4 27.1 26.2 25.1 1940-1979 27.6 27.8 27.4 27.1 26.3 25.3 1980-2009 28.1 28.2 27.8 27.4 26.5 25.6 T, oC 0.50 0.60 0.40 0.30 0.30 0.50 A summary of the average monthly temperature, average maximum temperature, and average minimum temperature from 1900 to 2010 for San Juan, PR is shown in Table 3. In order to better visualize temperature changes, average monthly temperatures were calculated in thirty years period, the results are shown in Table 4.



Table 3. Summary Table for San Juan, PR – Latitude: 18.43’; Longitude: 66.0; Altitude: 18 m. Month Jan Feb March April May June Avg. Temp. oC 24.4 24.4 24.8 25.5 26.4 27.1 Avg. Max. Temp. oC 26.1 26.3 26.8 27.7 28.8 29.5 Avg. Min. Temp. oC 22.9 22.7 23.2 23.4 24.2 25.2 Standard Deviation 0.776 0.912 0.914 1.01 0.984 0.953 % RSD 3.18 3.75 3.69 3.98 3.72 3.51 Month July Aug Sept Oct Nov Dec Avg. Temp. oC 27.3 27.5 27.4 27.1 26.1 25.0 Avg. Max. Temp. oC 29.6 29.5 29.2 29.2 27.9 26.7 Avg. Min. Temp. oC 25.9 25.9 25.8 25.2 24.8 23.6 Standard Deviation 0.877 0.835 0.815 0.848 0.720 0.721 % RSD 3.21 3.03 2.97 3.13 2.76 2.88 Table 4. Average monthly 40 years temperatures for San Juan, PR. Year -Jan- -Feb- -Mar- -Apr- -May- -Jun- 1900-1939 23.8 23.6 23.9 24.5 25.6 26.2 1940-1979 24.1 24.0 24.6 25.1 26.1 26.7 1980-2009 25.1 25.2 25.6 26.5 27.4 28.2 T, oC 1.3 1.6 1.7 2.0 2.1 2.0 Year -Jul- -Aug- -Sep- -Oct- -Nov- -Dec- 1900-1939 26.6 26.7 26.6 26.2 25.4 24.4 1940-1979 26.9 27.2 27.2 26.9 25.9 25.0 1980-2009 28.3 28.4 28.2 27.9 26.8 25.7 T, oC 1.7 1.7 1.6 1.7 1.4 1.3 For San Juan PR the average temperature for a forty year period increased between 1.3oC and 2.1oC for each month between 1900 and 2009, the overall average temperature increase was 1.7oC which is higher than previous studies and projections and significant higher than Ponce, PR. A plot for monthly temperatures vs. year showed positive slopes for each month between 1900 and 2010, an indication of the gradual temperature increase for the last one hundred and ten years. CONCLUSION Average surface temperature data for two municipalities in Puerto Rico showed a steady increase from 1900 to 2010. The average increase in temperature for San Juan was 1.7oC and 0.48oC for Ponce. The increase in temperature is an effect of global warning that is evident for Puerto Rico as for other parts of the world. ACKNOWLEDGMENT The author wishes to express his gratitude to Ms. Susan Soltero, meteorologist, Univision-PR and Ms. Odalys Martínez of the National Oceanic and Atmospheric Administration for their assistance in the gathering of the information.


Sabía usted ………….

El calentamiento global Es el aumento de la temperatura media de la atmósfera de la Tierra y los océanos desde finales del siglo XIX y su continuación proyectada. Desde principios del siglo XX, la temperatura media superficial de la Tierra ha aumentado aproximadamente 0.8°C (1.4 ° F), con cerca de dos tercios del aumento desde 1980. El calentamiento del sistema climático es inequívoco, y los científicos están más del 90% seguros de que es causado principalmente por el aumento en las concentraciones de gases de efecto invernadero producidas por actividades humanas como la quema de combustibles fósiles y la deforestación. . (por Carlos M. Vélez) ¿Qué es la química verde? Se trata de una filosofía que consiste en el esfuerzo colectivo para reducir al mínimo, o de ser posible eliminar por completo la contaminación desde su inicio: mediante el uso de procesos “limpios”, evitando al máximo el desperdicio o uso indiscriminado de materias primas no renovables, así como el empleo de materiales peligrosos o contaminantes en la elaboración de productos químicos “limpios”, que no atenten contra la salud o el ambiente. Los medios que utiliza la química verde se centran en la disminución o la eliminación del uso de productos químicos tóxicos y el reciclaje de los desechos producidos por el avance tecnológico, de una manera creativa de tal forma que se consiga un mínimo impacto a los seres humanos y al medio ambiente, sin sacrificar el avance científico y tecnológico. Existen además de la química verde otros medios para prevenir la generación de contaminantes, como los controles de ingeniería, el control de inventarios y la optimización de procesos. La diferencia entre la química verde y la química del ambiente es que mientras esta última tiene como objetivo el saneamiento y remediación de los efectos en el ambiente de los procesos contaminantes, la química verde intenta prevenir la contaminación en su origen.



COLEGIO DE QUÍMICOS DE PUERTO RICO Auspicia el Certamen de Arte – Afiche

Conoces a algún estudiante de 4to a 10mo Grado, para que le dejes saber que puede inscribirse en el Certamen de Afiches en o antes del 1 de mayo de 2013. Esta es su oportunidad de participar y tener una experiencia extraordinaria con la Química en Puerto Rico. OBJETIVOS DEL CERTAMEN a) Reconocer sobre la importancia de la Química en la vida cotidiana dentro del Hogar. b) Destacar los logros y avances de la química en el hogar. c) Promover la participación de estudiantes en el Certamen de Afiches sobre Química. d) Educar y capacitar a los estudiantes teniendo como principal motivación el manejo y las

virtudes de la química. e) Motivar el aprendizaje de la Química entre los jóvenes en Puerto Rico. f) Generar un sentido de orgullo de estudiar química ante la diversidad de esta rama de la ciencia. INSCRIPCIÓN Y APORTACION (efectivo solamente) Individual $ 2.00 Equipo desde 2 hasta 3 participantes $ 5.00 en total

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THE USE OF SPIDER WEB AS COLLECTION MEDIA TO DETERMINE INDOOR AIR METAL CONTAMINATION

Rafael Infante Méndez Professor of Chemistry Caribbean University 1015 La Ceiba Ave.

Ponce, Puerto Rico 00731 [email protected]

ABSTRACT The purpose of this investigation is to determine if spider web could be used as a passive collection media for aerosols and particulate matter. A sample of a spider web located in a popular pub was collected and analyzed for trace metals contaminants. The results shows that most of the metals detected are associated with cigarette smoking. Spider web proved to be a useful collection media to determine indoor metal pollution. INTRODUCTION A spider web is a device built by a spider out of spider silk extruded from its spinnerets. Webs allow a spider to catch prey without having to expend energy by running it down. Thus it is an efficient method of gathering food. However, constructing the web is in itself an energetically costly process because of the large amount of protein required, in the form of silk. In addition, after a time the silk will lose its stickiness and thus become inefficient at capturing prey. It is common for spiders to eat their own web daily to recoup some of the energy used in spinning. The silk proteins are thus recycled. The tensile strength of spider silk is greater than the same weight of steel and has much greater elasticity. Its microstructure is under investigation for potential applications in industry, including bullet-proof vests and artificial tendons. These characteristics has made spider web a useful passive natural collection media for aerosols and particulate matter both in indoor and outdoor environments. In addition spider web have been proposed as passive aerosol collector to protect against chemical, biological, radiological and nuclear material6. Analysis of spider webs from limestone arches in New South Wales, Australia showed levels of lead and zinc to be several times higher at Jenolan Caves than reference sites at Abercrombie and Wombeyan Caves. The high concentrations at Jenolan were attributed to emissions from motor vehicles that travel through the arch. Analysis of water-soluble ions in webs from Jenolan and 6 THE USE OF SPIDER WEBS AS PASSIVE BIOAEROSOL COLLECTORS. Thesis by Daniel I. Mattei, Major, DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY. AIR FORCE INSTITUTE OF TECHNOLOGY, Wright-Patterson Air Force Base, Ohio



Abercrombie Caves showed large differences between the sites, which could be explained by differences in the geology and biology of the cave environments. Spider webs proved useful indicators of environmental chemistry and undoubtedly have applications beyond the cave environments studied here.7 Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the home. High temperature and humidity levels can also increase concentrations of some pollutants. There are many sources of indoor air pollution. These include combustion sources such as oil, gas, kerosene, coal, wood, and tobacco products; building materials and furnishings as diverse as deteriorated, asbestos-containing insulation, wet or damp carpet, and cabinetry or furniture made of certain pressed wood products; products for household cleaning and maintenance, personal care, or hobbies; central heating and cooling systems and humidification devices; and outdoor sources such as radon, pesticides, and outdoor air pollution. A spider web sample was collected from a well-attended pub located in the municipality of Ponce, PR near the Ponce Port. Nearby pollution sources include the port, a metal recycling facility, and the sea aerosol. The pub has wide windows and doors for ventilation and has no air conditioner. Smoking in the pub is allowed. EXPERIMENTAL The spider web collected hanged from the ceiling of the pub located just above the dispatch bar. A piece of the web was taken and stored in a sterile plastic bag and transported to the laboratory for analysis. The web was acid digested following standard procedures8. The acid digestate was diluted and analyzed using Induced Couple Plasma – Optical Emission Spectroscopy (ICP-OES). The ICP-OES used was a Thermo Jarrell Ash 61E-Tracer following method SW-846 6010C9. RESULTS AN DISCUSSION Table 1 summarizes the metals found in the spider web; concentration is given in total nanograms found in the web analyzed.

7 Spider webs as environmental indicators. Hose G. C.; James J. M.; Gray M. R. Environnemental Pollution. 2002, vol. 120, no3, pp. 725-733 (32 references). 8 Environmental Protection Agency. SW-846 Methods, Third Edition. Method 3050B, Acid Digestion of Sediments, Sludge, and Soils. 9 Environmental Protection Agency. SW-846 Methods, Third Edition. Method 6010C, Inductively Coupled Plasma-Atomic Emission Spectroscopy.


Table 1. Metal Found in Spider Web. To determine the possible source of the metals found in the spider web, enrichment factors (EFs) were calculated against Silicon which is a metal associated with natural sources such as Earth crust and the sea water aerosol. The use of EFs is very popular as a means of identifying and quantifying the anthropogenic origin of certain elements since the 1970s. EFs were calculated as follow:

EF = {[Metal]web/[Si]web} / {[Metal]Earth’s crust/[Si]Earth’s crust}

The results are shown in Table 2.

Table 2. Enrichment Factors Relative to Si.

METAL ENRICHMENT FACTOR RELATIVE TO

PROBABLE SOURCE

EARTH CRUST SEA WATER

Sb 5.3 x 104 2.0 x 102 SEVERAL

As 2.5 x 104 8.5 x 101 SEA AEROSOL

Ba 2.9 X 103 1.2 X 102 SEVERAL

Be 1.8 X 102 2.1 X 103 METAL RECYCLING

Cd 1.2 X 105 1.3 X 103 CIGARETTE SMOKE

Cr 1.5 X 103 1.3 X 103 CIGARETTE SMOKE

Co 1.2 X 103 1.6 X 103 CIGARETTE SMOKE

Cu 1.0 X 104 8.7 x 102 METAL RECYCLING

Fe 1.2 X 103 9.6 X 104 METAL RECYCLING

METAL ng/WEB METAL ng/WEB Al 2.4 x 107 Mg 1.6 x 107 Sb 4.4 x 103 Mn 7.0 x 105 As 2.2 x 104 Mo 4.6 x 103 Ba 4.1 x 105 Ni 1.1 x 105 Be 1.4 x 102 K 1.9 x 107 Cd 7.3 x 103 Se 1.8 x 103 Ca 1.6 x 108 Si 1.1 x 105 Cr 8.6 x 104 Ag < 7.5 x 101 Co 1.5 x 104 Na 2.3 x 107 Cu 2.9 x 105 Tl 5.9 x 103 Fe 3.2 x 107 V 1.2 x 105 Pb 2.1 x 105 Zn 2.1 x 106



Table 2. Enrichment Factors Relative to Si (Cont.)

METAL ENRICHMENT FACTOR RELATIVE TO

PROBABLE SOURCE

EARTH CRUST SEA WATER

Sb 5.3 x 104 2.0 x 102 SEVERAL

Pb 5.1 x 104 6.3 x 104 CIGARETTE SMOKE

Mn 1.5 x 103 3.1 x 103 METAL RECYCLING

Mo 1.0 X 104 4.1 SEA AEROSOL

Ni 2.9 X 103 4.8 X 102 METAL RECYCLING

Se 8.7 X 104 3.5 X 101 SEA AEROSOL

Tl 2.7 X 104 5.2 X 104 FUEL/SEVERAL SOURCES

V 1.5 X 103 7.0 X 102 FOSIL FUEL

Zn 4.8 X 103 3.8 x 103 CIGARETTE SMOKE

CONCLUSIONS Spider webs are useful as a passive collection media to assess indoor air pollution. The sources of the metals found in the web were identified. Cigarette smoking contributes to the indoor concentration of the most toxic metals such as: Cd, Cr, Co, Pb, and Zn. Local and distant sources such as the metal recycling facility, fossil fuels use, and the sea aerosol were also identified.

Sabía usted…………. Drogas, redes y arañas En 1948, el suizo farmacólogo P. N. Witt comenzó su investigación sobre el efecto de las drogas en las arañas. Witt ensayó en las arañas con una gama de drogas psicoactivas, incluyendo la anfetamina, mezcalina, estricnina, LSD y cafeína hallando que las drogas afectan el tamaño y la forma de las redes de la araña, en lugar de la hora cuando la construye. En pequeñas dosis de cafeína (10 µg/araña), las redes eran más pequeñas; los radios fueron desiguales, pero la regularidad de los círculos no se afectaba. En dosis más altas (100 µg/araña), la forma cambiaba más, y el diseño de la red se volvió en irregular. Todas las drogas probaron reducir la red regularidad excepto las pequeñas dosis de LSD (0.1–0.3 µg), que produjeron redes mas ordenadas. (por Carlos M. Vélez)


Sabía usted…………. El desarrollo laboral de la Química en Puerto Rico se ha distinguido en los siguientes sectores:

La caña de azúcar y las centrales en Puerto Rico Teodoro Moscoso y el Laboratorio de Fomento Planta Piloto de Ron (UPR) Estación Experimental Agrícola (UPR) La industria petroquímica e industrias aliadas La industria de alimentos y bebidas La industria farmacéutica y dispositivos médicos La industria bioquímica y biotecnología Química forense Academia a nivel elemental hasta post grado universitario Ambiental y Nanotecnología

LA REVISTA EL CRISOL ESTÁ DISPONIBLE PARA PUBLICAR SU

ANUNCIO. PARA MAYOR INFORMACIÓN COMUNICARSE AL 787-763-6070

Y COORDINAR UNA REUNIÓN DE ORIENTACIÓN CON LA JUNTA

EDITORA.



CHARACTERIZATION OF NITROPRUSSIDES

Héctor J. Acosta UNIVERSIDAD DEL TURABO

Escuela de Ciencia y Tecnología / Centro de Estudios Doctorales Programa Doctoral en Ciencias Ambientales

April 2012

. Nitroprussides are a complex intermediate acid that features an octahedral ferrous center surrounded by five tightly bound cyanide ligands and one linear nitric oxide ligand. They are synthetized from a reaction between nitric acid and potassium ferrocyanide to form salts. They also can be synthetized using nitric acid and copper cyanide in which case it forms a octahedral copper centered complex. Nitroprussides are coordination polymers produced from a cyanide and a transition metals and an acid with dielectric properties. Its chemical formula is mostly M[M(CN)₅NO] , Na₂[Fe(CN)₅NO} or Na₂[Cu(CN)₅NO], formed with a transition metal (Mn, Zn, Cd, Ni, Cu) and an alkaline earth metal (Na, Be, Mg, Ca, Ba, Cs).

The molecular symmetry is C₄. Linear nitrosyl ligands are assigned a single positive charge, thus the iron is assigned an oxidation state of 2⁺. As such it has a low-spin d⁶ electron configuration and is diamagnetic. Its chemical reactions are mainly associated with the NO ligand. Nitroprussides of divalent transition metals form a family of microporous molecular materials. Their properties in this sense depend on the transition metal cation involved and also on the preparative method, which determine their crystal structures. The stable phases of this family of materials belong to one of the following crystal structures: orthorhombic (Mn, Fe, Zn, and Cd), cubic (Co and Ni), and orthorhombic (Cu). These materials are stable up to 160⁰C while their dehydration takes place around 100⁰C. On dehydration copper complex changes into a tetragonal phase. The microporous nature of these materials depend on their crystal structure and correlating structure and adsorption data. The accessibility to the pore system is evaluated through adsorption of H₂O, CO₂, and N₂. Pores of both orthorhombic and cubic structures are to H₂O and CO₂ in experiments carried out at 23 and 0⁰C, respectively, but they are inaccessible to N₂ at -196⁰C. This behavior is related to the large polarizing power of the nitrosyl (NO) ligand which distorts the local environment of the iron atom and reduces the effective window cross section. The small pores of tetragonal copper nitroprussides were innaccesible to the adsorbates used.


Other alkali metal nitroprussides have different properties as those transition nitroprussides, like sodium salt nitroprusside with formula Na₂[Fe(CN)₅NO]·H₂O which is a potent vasodilator. This group of nitroprusside are mostly useful in medical pharmacology. Spectroscopic studies have shown that rare-earth alkali metal nitroprussides have a crystal structure formed by a tridimensional assembling of the [Fe(CN)₅NO] molecule block through iron bonds bounded at the N end of the CN ligands. The anion is located in sites of C₄ symmetry and the hydration water is strongly asymmetric, forming H-bonds of different strength. The sodium atoms, for sodium nitroprusside, are located in the octahedral positions. Alkali earth nitroprusside salts are used in pharmacology and medicine as vasodilators agents, diabetic controller and ventricular function regulator, while transition metals nitroprussides structural configuration is relevant to the use of Mn, Cd and Zn compounds as ion exchangers and particularly to the sorption of Cs from radioactive waste solutions. Mn, Cd and Zn nitroprussides have porous framework useful for adsorption and storage of small molecules.(R. Martinez, 2004). CHARACTERIZATION The crystal structure of Mn, Zn, and Cd transition nitroprussides in their anhydrous state were refined and analyzed fron X-ray Diffraction and powder patterns using the Rietveld method. Water crystallization was removed by heating below 100 ⁰C without disrupting the 3D network by introducing certain structural modification mainly around the M site. The compounds were found to be orthorhombic with space group coordenates: a = 13.784, b = 7.375, c = 10.947 for Mn, and a = 13.956, b = 7.504, c = 11.0230 for Cd. Anhydrous zink nitroprusside crystallizes in rhombohedral shape with space group: a = b = 19.252, c = 17.1707 and an angle θ= 90⁰. The structural information from XRD was complemented with thermo-gravimetric, Infrared and Mossbauer spectroscopy data. These compounds have a porous frame work useful for adsorption and storage of small molecules. The coordinate results for these transition metals nitroprussides are compared with an alkali metal nitropruside to determine the crystal structure of the alkali nitroprusside. We can assume that the nitrogen atoms occupy the six faces of the orthorhombic figure, the iron (Fe) is in one of the octahedral positions, and the five carbons, one or two metal atoms and the oxygen occupy the lineal positions of the cubic cell. Transition metal nitroprussides have orthorombic and rhomhedral crystal structures and earth alkaline metals nitroprussides have cubic crystal structures. As I said before, x-Ray Diffraction is complemented with other techniques like Mossbauer Spectroscopy and Infrared Spectrosocopy to characterize the crystal structure of nitroprussides. Nitroprussides of the rare-earth elements and some mixed rare-earth sodium nitroprussides are studied by Mossbauer spectroscopy at ambient and lower temperatures. Comparison of Raman and Infrared spectroscopy as complementary techniques for crystal structure analysis of nitroprussides has shown extreme weakness of the Raman-active phonons in specific regions. Infrared spectroscopic analysis has shown to work and give better results with infrared polarized light. An interesting feature of the infrared spectra of partially deuterated samples of sodium nitroprussides is the fine structure observed for each of the HDO vibrational modes.



Otherwise the high precision Mossbauer measurements reveal fine changes in the electronic configuration of the nitroprusside anions. Measurements with Mossbauer spectroscopy have confirmed the coordenates of the possible crystal structure determine by x-Ray Diffraction. A small increase of the quadrupole splitting reveals charge polarization effects in the nitroprusside anion caused by the oblate or prolate shape of the rare-earth ion and the lanthanide contraction. The doublet of the quadrupole splitting is clearly shown in an spectrogram of a nitroprusside molecule by Mossbauer spectroscopy. This spectrogram is typical for each nitroprusside which allows the calculation of the quadrupole splitting factor and the electric field gradient asymmetry parameter caused by polarizability and determination of the symmetry and crystal structure of nitroprussides. (V. Russanov, 2009). The chemical shift and QS of a nitroprusside allows the calculation of a factor which is the distance between the base of the doublets in the spectrogram. There is a specific factor for each metal, earth alkaline or transition, which is a standard reference for the metal in the Mossbauer spectroscopy. This factor allows us to identify the metal in the crystal structure of nitroprussides and some other information on the molecular of the compound studied. It has been reported that the value of one of the main Mossbauer parameters, the IS, is slightly dependent on the type of the counter ion in the composition of the nitroprusside. Structural data on various nitroprussides show that the counter ions are bound to the equatorial cyanide groups. The main component of the electric field gradient (EFG) is perpendicular to the equatorial plane of the nitroprusside anion and collinear with the main symmetry axis N-C-Fe-N-O. (Rusanov 2009). So far we understand that we can use x-Ray Diffration to determine the coordenates and the angle of the structure of nitroprusside. Using Infrared Spectroscopy we can confirm the coordenates for the crystal structure, and with the Mossbauer spectroscopy we can identify the metal or metals in the structure to design the crystal structure of the nitroprussides. We have also learned that we have to use several complementary techniques to characterize and identify any material. It is hardly difficult to rely on one technique only. We have already established that alkali rare-earth metals nitroprussides are used mostly in pharmacology and medicine. But we are mostly interested in adsorbent materials for environmental applications. Let us take a closer look at the properties and microporous nature of the transition metals nitroprussides. Nitroprussides of divalent transition metals form a family of microporous molecular materials. Their properties, in this sense, depend on the transition metal cation involved and also on the preparative method, which determine their crystal structure. Since only the N atoms of the CN ligands are able to link to the evolved cations, in a tridimensional structure the NO ligand always remains unlinked to the O end. This leads to materials with a system of channels appropriate for small molecules separation. The formation of an additional system of bigger and interconnected pores depends on the crystal structure adopted by the complex salt, and it is related to the occurrence of structural vacancies of both the complex anions and the cations.


This family of materials show a pronounced polymorphic character. Slowly grown crystals of Mn²⁺, Fe²⁺, and Cd²⁺ nitroprussides result in monoclinic trihydrates, while remaining within the mother liqueur when formed. For Zn²⁺ the obtained crystals are hexagonal trihydrate. When these trihydrates, both monoclinic and hexagonal loose a water molecule to form orthorhombic which are the stable phase for these four cations. All the stable phases of the studied family of materials belong to one of the following crystal structures: orthorhombic (Mn, Fe, Cu, Zn), cubic: (Co and Ni). In all these structures the iron atom is coordinated to five C atoms of CN ligands and to the N atoms of the NO group. The resulting octahedron [Fe(CN)₅NO) is distorted due to the large electron withdrawing effect of the nitrosyl group (NO) with respect to the cyanide ligand. (Balmaseda, 2003). References: “On the Microporous Nature of Transition Metal Nitroprussides” J.Balmaseda, E. Reguera, A.Gomez. University of La Havana. Journal of Physical Chemistry. ACS Publications. Sept. 23, 2003. 107 (4), pp. 11360 – 11369 “Vibrational Spectra of single-crystal sodium nitroprusside. II. Polarized infrared spectra and normal-coordinate analysis”. Inorganic Chemistry. ACS Publications. John B. Bates, R.K. Khanna. June 1970, 9 (6), pp. 1376-1380. “Mossbauer spectroscopic studies of the alkali metal and transition metal nitroprussides” P.S. Goel, A.H. Garg. Inorganic Chemistry. ACS Publications. July 1971. 10(7). Pp. 1344-1347 “Vibrational spectrum of sodium nitroprusside. Normal coordinate analysis for the Fe(CN)₅NO²¯ Ion”. G. Pallani, A. Poletti, A. Santucci. Journal of Molecular Structure, ACS. Volume 8, issue 1-2, april 1971, pp 63-74. “The interpretation of the Mossbauer spectra of reduced sodium nitroprusside”. J.B. Raynor. Journal of Inorganic and Nuclear Chemistry. Elsevier Chem. May 16, 2003. “Hydrogen Storage in Porous transition Metals Nitroprussides” Universidad de la Habana. L. Reguera, J.Balmaseda, C.P. Krapp and E. Reguera. Journal of Physical Chemistry, ACS. June 20, 2008. 112 (28), pp. 10490-10501. “Structural Effects and interactions of Carbon Dioxide molecules adsorbed on Ni, Zn, and Cd Nitroprussides”. R.Roque-Malherbe, O.N.C. Uwakwehs, C.Lozano, R. Polanco, A.Hernandez Maldonado, P. Fierro, F. Lugo and J.N. Primera Pedrozo. Journal of Physical Chemistry. ACS July 2, 2011. 115(31), pp. 15555-15569. “Determination of the Mossbauer parameters of rare-earth nitroprussides: Evidence for new light-induced state (LIMES) in nitroprussides”. V. Rusanov, S. Stankov, A. Ahmedova, A.X. Trautwein. Journal of Solid State Chemistry. Volume 182, issue 5, may 2009. Pp. 1252-1259.



“Thermal behavior and vibrational spectra of Cesium nitroprusside monohydrate”. M.M. Vergara, E.I. Varetti. Journal of Physics and Chemistry of Solids. Volume 48, issue 1, 1987. pp. 13-19. ____________________________________

Sabía usted que …………………… Además, el SNP es utilizado por los químicos forenses en una prueba preliminar en la identificación de sustancias ilícitas. La prueba, llamada Prueba de Simón, se realiza añadiendo un volumen de una solución de SNP y acetaldehído en agua deionizada a una supuesta droga, a la cual se le añade seguida 2 volúmenes de una solución acuosa de carbonato de sodio. La prueba se vuelve azul para algunas aminas secundarias. Las aminas secundarias más comunes encontradas en Química Forense incluyen 3, 4-metilenedioximetanfetamina (MDMA, el componente principal en Éxtasis) y fenetilaminas como metanfetamina. (por Carlos M. Vélez) CONVENCIÓN DE PRIMAVERA El Colegio de Químicos de Puerto Rico ofrecerá los días 26 al 28 de abril de 2013 la Convención de Primavera en el Parador Parguera en Lajas, Puerto Rico. Se estarán ofreciendo cursos del Programa de Educación Continuada. Separa tu curso a través de la página electrónica del Colegio de Químicos de Puerto Rico. Registro de Cursos por día (viernes y sábado) $ 130 Colegiado / No Colegiado $ 160 Incluye meriendas y almuerzos Registro de Curso (domingo) Sujeto a asistencia mínima requerida (30 participantes) $ 70 Colegiado / No Colegiado $ 90 Incluye merienda

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Edición 4ta. El Crisol

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