Natural Gas location design and operation

A major determinant of the level of effective natural gas supply is the ease to feed customers, minimizing system total costs. The aim of this work is the study of the right number of Gas Supply Units – GSUs - and their optimal location in a gas network. This paper suggests a GSU location heuristic, based on Lagrangean relaxation techniques. The heuristic is tested on the Iberian natural gas network, a system modelized with 65 demand nodes, linked by physical and virtual pipelines. Lagrangean heuristic results along with the allocation of loads to gas sources are presented, using a 2015 forecast gas demand scenario.

Analysis of polycyclic aromatic hydrocarbons in fish: optimisation and validation of microwave-assisted extraction

An accurate and sensitive method for determination of 18 polycyclic aromatic hydrocarbons (PAHs) (16 PAHs considered by USEPA as priority pollutants, dibenzo[a,l]pyrene and benzo[j]fluoranthene) in fish samples was validated. Analysis was performed by microwave-assisted extraction and liquid chromatography with photodiode array and fluorescence detection. Response surface methodology was used to find the optimal extraction parameters. Validation of the overall methodology was performed by spiking assays at four levels and using SRM 2977. Quantification limits ranging from 0.15–27.16 ng/g wet weight were obtained. The established method was applied in edible tissues of three commonly consumed and commercially valuable fish species (sardine, chub mackerel and horse mackerel) originated from Atlantic Ocean. Variable levels of naphthalene (1.03–2.95 ng/g wet weight), fluorene (0.34–1.09 ng/g wet weight) and phenanthrene (0.34–3.54 ng/g wet weight) were detected in the analysed samples. None of the samples contained detectable amounts of benzo[a]pyrene, the marker used for evaluating the occurrence and carcinogenic effects of PAHs in food.

Determinação de germânio em alimentos por espectrometria de massa ligada a um plasma acoplada indutivamente (ICP-MS)

Nos dias de hoje existe uma grande preocupação da população em fazer uma alimentação mais saudável, uma alimentação que tenha nos seus alimentos elementos que não prejudiquem a saúde mas sim que a tornem mais forte. Um desses elementos que pode trazer benefício para a saúde é o Germânio, elemento de estudo no presente trabalho. Neste trabalho determinou-se a concentração de Germânio em alguns alimentos. Os alimentos usados foram: espargos, ginseng, cogumelos, rabanete, gengibre, aloé vera e alho. Para se fazer a decomposição das amostras foi usada uma solução de ácido nítrico concentrado (67%) e peróxido de hidrogénio (30%), de seguida as soluções resultantes foram analisadas por espectrometria de massa ligado a um plasma acoplado indutivamente (Inductive Coupled Plasma - Mass Spectrometry (ICP-MS)). Esta técnica permitiu estudar os três isótopos mais abundantes de germânio (Ge70, Ge72 e Ge74). Como principais resultados deste trabalho pode-se referir que o alimento que apresenta uma maior concentração de Germânio é o ginseng (243,0 ng/g), seguindo-se o alho (152,6 ng/g). Com concentrações bastante próximas ficaram os espargos, gengibre e cogumelos com um valor aproximado de 75 ng/g. As concentrações mais baixas formam encontradas no aloé vera e rabanete, com valores de 38,16 e 21,85ng/g respectivamente. Com estes resultados podemos concluir que para ter uma alimentação rica neste elemento deve-se ingerir ginseng e alho pois dos alimentos estudados são os mais ricos em Germânio.

Implementação e validação de um método para determinação de contaminantes em vinho por microextração em fase sólida e gc-ms/ms e sua correlação com a análise sensorial

Cada vez mais começa a notar-se, na indústria vitivinícola, uma grande preocupação com a qualidade dos seus produtos, motivada pela maior sensibilização e exigência dos consumidores. Deste modo, a presença de defeitos organoléticos no vinho representa uma fonte de perda financeira nesta indústria, pelo que o seu controlo se torna indispensável para que se obtenha um produto de elevada qualidade. Neste sentido, torna-se interessante desenvolver um método de análise que seja rápido de forma a permitir a quantificação simultânea das moléculas identificadas como principais responsáveis pelos distúrbios olfativos dos vinhos. Assim, este trabalho surge com o objetivo de implementar e validar um método para a determinação de contaminantes em vinho por microextração em fase sólida (SPME) e cromatografia gasosa acoplada à espetrometria de massa tandem (GC-MS/MS) e a sua correlação com a análise sensorial. A técnica de microextração em fase sólida é simples e rápida na medida em que não requer um pré-tratamento da amostra. Por sua vez, a análise por GC-MS permite identificar de forma clara os compostos em estudo, nomeadamente, 4-Etilfenol (4-EP), 4-Etilguaiacol (4-EG), 2,4,6-Tricloroanisol (TCA), 2,3,4,6-Tetracloroanisol (TeCA) e 2,4,6-Tribromoanisol (TBA). Foram realizados estudos de otimização das condições de extração, comparando as fibras 100 μm PDMS e 50/30 μm DVB/CAR/PDMS. Obtiveram-se resultados mais satisfatórios, em termos de resposta e da relação sinal/ruído, com a fibra 50/30 μm DVB/CAR/PDMS e estabeleceram-se como condições de extração 55ºC para a temperatura de incubação/extração, uma velocidade de agitação de 250 rpm e 60 minutos de tempo de extração. Ao longo deste trabalho, analisaram-se 50 amostras de vinho, das quais 48 eram amostras de Vinho Tinto do Douro e 2 de Vinho do Porto. Para validar a metodologia foram realizados estudos de linearidade, limiares analíticos, repetibilidade, precisão intermédia e recuperação. De um modo geral, obtiveram-se bons resultados ao nível da linearidade para as gamas de concentração escolhidas. Quanto aos limites de deteção e de quantificação, o 4-EP é o contaminante que apresenta uma gama de concentrações mais alta, notando-se limiares analíticos mais elevados, com valores próximos dos últimos níveis de concentração, oscilando entre 65 e 583 μg/L. No caso dos Anisóis, o TBA apresenta limites de deteção mais baixos, entre 0,4 e 17,0 ng/L. Os limiares analíticos foram validados com recurso a estudos de precisão intermédia e repetibilidade, cujos resultados se encontram dentro das especificações descritas no documento SANCO/10684/2009 (%RSD ≤ 30% para os Anisóis e %RSD ≤ 20% para os Fenóis Voláteis). Foram, ainda, realizados estudos de exatidão recorrendo a ensaios de recuperação e a ensaios interlaboratoriais. Muitas vezes conseguem-se boas recuperações, no entanto notam-se maiores dificuldades para o TBA e para o TeCA. Relativamente aos ensaios interlaboratoriais, verificam-se maiores discrepâncias para o 4-EP. Já os restantes contaminantes apresentam resultados, geralmente, satisfatórios (|z-score| ≤ 2).

Analysis of polycyclic aromatic hydrocarbons in fish: evaluation of a quick, easy, cheap, effective, rugged, and safe extraction method

QuEChERS method was evaluated for extraction of 16 PAHs from fish samples. For a selective measurement of the compounds, extracts were analysed by LC with fluorescence detection. The overall analytical procedure was validated by systematic recovery experiments at three levels and by using the standard reference material SRM 2977 (mussel tissue). The targeted contaminants, except naphthalene and acenaphthene, were successfully extracted from SRM 2977 with recoveries ranging from 63.5–110.0% with variation coefficients not exceeding 8%. The optimum QuEChERS conditions were the following: 5 g of homogenised fish sample, 10 mL of ACN, agitation performed by vortex during 3 min. Quantification limits ranging from 0.12– 1.90 ng/g wet weight (0.30–4.70 µg/L) were obtained. The optimized methodology was applied to assess the safety concerning PAHs contents of horse mackerel (Trachurus trachurus), chub mackerel (Scomber japonicus), sardine (Sardina pilchardus) and farmed seabass (Dicentrarchus labrax). Although benzo(a)pyrene, the marker used for evaluating the carcinogenic risk of PAHs in food, was not detected in the analysed samples (89 individuals corresponding to 27 homogenized samples), the overall mean concentration ranged from 2.52 l 1.20 ng/g in horse mackerel to 14.6 ± 2.8 ng/ g in farmed seabass. Significant differences were found between the mean PAHs concentrations of the four groups.

Analysis of polycyclic aromatic hydrocarbons in atmospheric particulate samples by microwaveassisted extraction and liquid chromatography

A methodology based on microwave-assisted extraction (MAE) and LC with fluorescence detection (FLD) was investigated for the efficient determination of 15 polycyclic aromatic hydrocarbons (PAHs) regarded as priority pollutants by the US Environmental Protection Agency and dibenzo(a,l)pyrene in atmospheric particulate samples. PAHs were successfully extracted from real outdoor particulate matter (PM) samples with recoveries ranging from 81.4±8.8 to 112.0±1.1%, for all the compounds except for naphthalene (62.3±18.0%) and anthracene (67.3±5.7%), under the optimum MAE conditions (30.0 mL of ACN for 20 min at 110ºC). No clean-up steps were necessary prior to LC analysis. LOQs ranging from 0.0054 ng/m3 for benzo( a)anthracene to 0.089 ng/m3 for naphthalene were reached. The validated MAE methodology was applied to the determination of PAHs from a set of real world PM samples collected in Oporto (north of Portugal). The sum of particulate-bound PAHs in outdoor PM ranged from 2.5 and 28 ng/m3.

Use and reuse of SPE disks for the determination of pyrethroids in water by GC-ECD

Seven pyrethroids (bifenthrin, fenpropathrin, k-cyhalothrin, permethrin, a-cypermethrin, fenvalerate, and deltamethrin) were extracted from water using C18 solid-phase extraction disks, followed by gas chromatography with an electron capture detector (GC-ECD) analysis. The limits of detection in water samples ranged from 0.5 ng L-1 (fenpropathrin) to 110 ng L- 1 (permethrin), applying the calibration graph. The effects of different numbers of (re)utilizations of the same disks (up to four times with several concentrations) on the recoveries of the pyrethroids were considered. The recoveries were all between 70 and 120% after four utilizations of the same disk. There was no difference between these recoveries at a confidence level of 95%.

Development and validation of a novel method for the analysis of chlorinated pesticides in soils using microwave-assisted extraction–headspace solid phase microextraction and gas chromatography–tandem mass spectrometry

A new procedure for determining eleven organochlorine pesticides in soils using microwave-assisted extraction (MAE) and headspace solid phase microextraction (HS-SPME) is described. The studied pesticides consisted of mirex, α- and γ-chlordane, p,p’-DDT, heptachlor, heptachlor epoxide isomer A, γ-hexachlorocyclohexane, dieldrin, endrin, aldrine and hexachlorobenzene. The HS-SPME was optimized for the most important parameters such as extraction time, sample volume and temperature. The present analytical procedure requires a reduced volume of organic solvents and avoids the need for extract clean-up steps. For optimized conditions the limits of detection for the method ranged from 0.02 to 3.6 ng/g, intermediate precision ranged from 14 to 36% (as CV%), and the recovery from 8 up to 51%. The proposed methodology can be used in the rapid screening of soil for the presence of the selected pesticides, and was applied to landfill soil samples.

Air pollution from traffic emissions in Oporto, Portugal: health and environmental implications

Air pollution represents a serious risk not only to environment and human health, but also to historical heritage. In this study, air pollution of the Oporto Metropolitan Area and its main impacts were characterized. The results showed that levels of CO, PM10 and SO2 have been continuously decreasing in the respective metropolitan area while levels of NOx and NO2 have not changed significantly. Traffic emissions were the main source of the determined polycyclic aromatic hydrocarbons (PAHs; 16 PAHs considered by U.S. EPA as priority pollutants, dibenzo[a,l]pyrene and benzo[j]fluoranthene) in air of the respective metropolitan area. The mean concentration of 18 PAHs in air was 69.9±39.7 ng m−3 with 3–4 rings PAHs accounting for 75% of the total ΣPAHs. The health risk analysis of PAHs in air showed that the estimated values of lifetime lung cancer risks considerably exceeded the health-based guideline level. Analytical results also confirm that historical monuments in urban areas act as passive repositories for air pollutants present in the surrounding atmosphere. FTIR and EDX analyses showed that gypsum was the most important constituent of black crusts of the characterized historical monument Monastery of Serra do Pilar classified as “UNESCO World Cultural Heritage”. In black crusts, 4–6 rings compounds accounted approximately for 85% of ΣPAHs. The diagnostic ratios confirmed that traffic emissions were the major source of PAHs in black crusts; PAH composition profiles were very similar for crusts and PM10 and PM2.5.

Analysis of PCBs in soils and sediments by microwave-assisted extraction, headspace-SPME and high resolution gas chromatography with ion-trap tandem mass spectrometry

A procedure for the determination of seven indicator PCBs in soils and sediments using microwave-assisted extraction (MAE) and headspace solid-phase microextraction (HS-SPME) prior to GC-MS/MS is described. Optimization of the HS-SPME was carried out for the most important parameters such as extraction time, sample volume and temperature. The adopted methodology has reduced consumption of organic solvents and analysis runtime. Under the optimized conditions, the method detection limit ranged from 0.6 to 1 ng/g when 5 g of sample was extracted, the precision on real samples ranged from 4 to 21% and the recovery from 69 to 104%. The proposed method, which included the analysis of a certified reference material in its validation procedure, can be extended to several other PCBs and used in the monitoring of soil or sediments for the presence of PCBs.

Groundwater from infiltration galleries used for small public water supply systems: contamination with pesticides and endocrine disruptors

Infiltration galleries are among the oldest known means used for small public water fountains. Owing to its ancestral origin they are usually associated with high quality water. Thirty-one compounds, including pesticides and estrogens from different chemical families, were analysed in waters from infiltration galleries collected in Alto Douro Demarcated Wine region (North of Portugal). A total of twelve compounds were detected in the water samples. Nine of these compounds are described as presenting evidence or potential evidence of interfering with the hormone system of humans and wildlife. Although concentrations of the target analytes were relatively low, many of them below their limit of quantification, four compounds were above quantification limit and two of them even above the legal limit of 0.1 lg/L: dimethoate (30.38 ng/L), folpet (64.35 ng/L), terbuthylazine-desethyl (22.28 to 292.36 ng/L) and terbuthylazine (22.49 to 369.33 ng/L).

Monitoring of ochratoxin a exposure of the Portuguese population through a nationwide urine survey — winter 2007

Ochratoxin A (OTA) is a mycotoxin produced by a variety of fungi, such as Penicillium verrucosum and Aspergillium spp., which has been found to have a wide number of potentially deadly toxic effects, and can enter the human organism through a variety of means. It then finds its way into the bloodstream and, after a lengthy process, is eventually excreted through the urine. It can thus be detected in its original form not only in blood samples but also in this biological medium. As such, and in an attempt to evaluate the exposure of the Portuguese population to this mycotoxin, morning urine samples were collected during the Winter of 2007, from each of five geographically distinct Portuguese locations — Bragança, Porto, Coimbra, Alentejo, and Algarve — and subjected to extraction by immunoaffinity columns and to OTA quantification through liquid chromatography coupled with fluorescence detection. Prevalent incidence was higher than 95% with Coimbra being the exception (incidence of 73.3%). In nearly all locations, the OTA content of most samples was found to be above the limit of quantification (LOQ) of 0.008 ng/ml. Indeed, excluding Coimbra, with an OTA content level of 0.014 ng/ml, all regions featured content values over 0.021 ng/ml.

Evaluation of ochratoxin A exposure degree in two Portuguese cities through wheat and maize bread consumption during the winter 2007

The occurrence of OTA in fresh and packed wheat and in maize bread and the evaluation of the exposure degree through their consumption in two Portuguese populations from Porto and Coimbra, during the winter of 2007, were studied. One hundred and sixty eight bread samples, 61 maize and 107 wheat, were analysed by liquid chromatography–fluorescence detection (LC–FD). The results showed that 84% of samples were contaminated, with a maximum level of 3.85 ng/g (above the EU maximum limit, 3 ng/g). Fresh wheat bread presented higher levels than packed wheat bread. Moreover, the traditional maize bread, in either city, was consistently more contaminated than wheat bread, 0.25 vs 0.19 ng/g, and 0.48 vs 0.34 ng/ g for Porto and Coimbra, respectively. Avintes maize bread showed the highest mean contamination and maximum levels. The higher estimated daily intake of OTA from both types of bread in the population of Coimbra compared to Porto reflects the higher average contamination of bread in the first city.

Occurrence of bisphenol A, estrone, 17b-estradiol and 17a-ethinylestradiol in Portuguese rivers

This study focused on the occurrence of several EDCs including bisphenol A, estrone (E1), the 17b-estradiol (E2) and 17a- thinylestradiol (EE2) in fourteen rivers of Portugal. Samples analysis revealed a widespread contamination of BPA especially in Ave, Cávado, Douro, Ferro, Sousa and Vizela Rivers. Achieving 98.4 ng/L for the highest concentration. The estrogens achieved above the method quantification limit (MQL) were E1 in Águeda River and E2 in Ave, Lima and Tâmega Rivers. The maximum concentration detected for E1 was 26.9 ng/L. EE2 was detected only below MQL.

Development of a simple analytical method for the simultaneousdetermination of paracetamol, paracetamol-glucuronide andp-aminophenol in river water

Paracetamol is among the most worldwide consumed pharmaceuticals. Although its occurrence in the environment is well documented, data about the presence of its metabolites and transformation products is very scarce. The present work describes the development of an analytical method for the simultaneous determination of paracetamol, its principal metabolite (paracetamol-glucuronide) and its main transformation product (p-aminophenol) based on solid phase extraction (SPE) and high performance liquid chromatography coupled to diode array detection (HPLC-DAD). The method was applied to analysis of river waters, showing to be suitable to be used in routine analysis. Different SPE sorbents were compared and the use of two Oasis WAX cartridges in tandem proved to be the most adequate approach for sample clean up and pre-concentration. Under optimized conditions, limits of detection in the range 40–67 ng/L were obtained, as well as mean recoveries between 60 and 110% with relative standard deviations (RSD) below 6%. Finally, the developed SPE-HPLC/DAD method was successfully applied to the analysis of the selected compounds in samples from seven rivers located in the north of Portugal. Nevertheless all the compounds were detected, it was the first time that paracetamol-glucuronide was found in river water at concentrations up to 3.57 μg/L.