Nephrotoxicity effects of the wood preservative chromium copper arsenate on mice: histopathological and quantitative approaches

Chromium copper arsenate(CCA)was used for the protection of wood building material suntil the restriction by EPA in2002. During a short period of time 14���24h,a comparative nephrotoxicity study was performed regarding the effects of CCA and its compounds per se. Histopathological and histochemical features were correlated with the concentration of the total arsenic and chromium in mice kidney. Animals were subcutaneously injected with CCA(7.2mg/kg arsenic and 10.2mg/kg chromium per body weight), CrO3 (10.2 mg/kg),As2O5 (7.2 mg/kg)andNaCl(0.9%) per se. The histopathological examination of the renal sections evidenced acute tubular necrosis in the groups of animals exposed to CCA(in both periods of time). Although the same contents of pentavalent arsenic and hexavalent chromium were injected in treated animals with CCA and with the prepared solutions of As2O5 and CrO3, the arsenic concentration on kidneys of CCA-exposed animals was much higher than those in animals exposed to As2O5 (32- and28-fold higher at 14 and 24h,respectively). However,the elimination of chromium seems to occur similarly in the kidneys of animals treated with CCA and CrO3 per se. Interactions among the components of CCA result in a marked decrease of the ability of kidney to eliminate simultaneously both analytes.The nephrotoxicity of CCA was higher than its components per se, evidencing a possible synergetic effect.

Evaluation of the total antioxidant capacity of flavored water and electrochemical purine damage by sulfate radicals using a purine-based sensor

In this study, a method for the electrochemical quantification of the total antioxidant capacity (TAC) in beverages was developed. The method is based on the oxidative damage to the purine bases, adenine or guanine, that are immobilized on a glassy carbon electrode (GCE) surface. The oxidative lesions on the DNA bases were promoted by the sulfate radical generated by the persulfate/iron(II) system. The presence of antioxidants on the reactive system promoted the protection of the DNA bases immobilized on the GCE by scavenging the sulfate radical. Square-wave voltammetry (SWV) was the electrochemical technique used to perform this study. The efficiencies of five antioxidants (ascorbic acid, gallic acid, caffeic acid, coumaric acid and resveratrol) in scavenging the sulfate radical and, therefore, their ability to protect the purine bases immobilized on the GCE were investigated. These results demonstrated that the purine-based biosensor is suitable for the rapid assessment of the TAC in flavors and flavored water.

Toxicity of chromated copper arsenate: a study in mice

Chromated copper arsenate (CCA) was widespread used as a chemical wood preservative with application in the construction of playground equipment, fences, jetties, and naval. Environmental protection agency (EPA) had limited the use of CCA-treated wood on 2002, due to probable implications on both human and environmental health. Although this fact, several industries pursue the use of this product within their manufactories. In addition, the durability of this wood for 60 years, makes these treated products an hazard to the public health. In the present work, studies were explored exposing mice to CCA, during 14, 24, 48, and 96 h for the assessment of acute toxicity of CCA. Kidney and liver were removed, prepared for histology and for metalloid, and copper content evaluation by high resolution inductively coupled plasma mass spectroscopy. The histological results evidenced apparently normal structures for control animals and group exposed to As2O5. On the contrary, the renal sections of the animals treated with CCA revealed epithelium cells desquamation, hyaline, and granular casts in renal tubules lumen. Furthermore, high levels of arsenic were detected in the kidney of animals treated with CCA over 14 and 48 h, being significantly greater than controls. Although this approach underlines the potential hazard of CCA on some vital organs, further testing may be required to establish the impacts on other functions.

Structural, physical, and chemical modifications induced by microwave heating on native agar-like galactans

Native agars from Gracilaria vermiculophylla produced in sustainable aquaculture systems (IMTA) were extracted under conventional (TWE) and microwave (MAE) heating. The optimal extracts from both processes were compared in terms of their properties. The agars��� structure was further investigated through Fourier transform infrared and NMR spectroscopy. Both samples showed a regular structure with an identical backbone, ��-D-galactose (G) and 3,6-anhydro-��-L-galactose (LA) units; a considerable degree of methylation was found at C6 of the G units and, to a lesser extent, at C2 of the LA residues. The methylation degree in the G units was lower for MAEopt agar; the sulfate content was also reduced. MAE led to higher agar recoveries with drastic extraction time and solvent volume reductions. Two times lower values of [��] and Mv obtained for the MAEopt sample indicate substantial depolymerization of the polysaccharide backbone; this was reflected in its gelling properties; yet it was clearly appropriate for commercial application in soft-texture food products.

Optimiza����o do tratamento de um efluente aquoso resultante da utiliza����o de cola nas m��quinas de produ����o de placas de madeira

O presente trabalho teve como principais objectivos, estudar e optimizar o processo de tratamento do efluente proveniente das m��quinas da unidade Cold-press da linha de produ����o da Empresa Swedwood, caracterizar a solu����o l��mpida obtida no tratamento e estudar a sua integra����o no processo, e por fim caracterizar o res��duo de pasta de cola obtido no tratamento e estudar a poss��vel valoriza����o energ��tica deste res��duo. Ap��s caracteriza����o inicial do efluente e de acordo com os resultados de um estudo pr��vio solicitado pela Empresa Swedwood a uma empresa externa, decidiu-se iniciar o estudo de tratabilidade do efluente pelo processo f��sico-qu��mico a coagula����o/flocula����o. No processo de coagula����o/flocula����o estudou-se a aplicabilidade, atrav��s de ensaios Jar-test, dos diferentes agentes de coagula����o/flocula����o: a soda c��ustica, a cal, o cloreto f��rrico e o sulfato de alum��nio. Os melhores resultados neste processo foram obtidos com a adi����o de uma dose de cal de 500 mg/Lefluente, seguida da adi����o de 400 mg/Lefluente de sulfato de alum��nio. Contudo, ap��s este tratamento o clarificado obtido n��o possu��a as caracter��sticas necess��rias para a sua reintrodu����o no processo fabril nem para a sua descarga em meio h��drico. Deste modo procedeu-se ao estudo de tratamentos complementares. Nesta segunda fases de estudo testaram-se os seguintes os tratamentos: a oxida����o qu��mica por Reagente de Fenton, o tratamento biol��gico por SBR (sequencing batch reactor) e o leito percolador. Da an��lise dos resultados obtidos nos diferentes tratamentos conclui-se que o tratamento mais eficaz foi o tratamento biol��gico por SBR com adi����o de carv��o activado. Prev��-se que no final do processo de tratamento o clarificado obtido possa ser descarregado em meio h��drico ou reintroduzido no processo. Como o estudo apenas foi desenvolvido �� escala laboratorial, seria ��til poder validar os resultados numa escala piloto antes da sua implementa����o industrial. A partir dos resultados do estudo experimental, procedeu-se ao dimensionamento de uma unidade de tratamento f��sico-qu��mico e biol��gico �� escala industrial para o tratamento de 20 m3 de efluente produzido na f��brica, numa semana. Dimensionou-se ainda a unidade (leito de secagem) para tratamento das lamas produzidas. Na unidade de tratamento f��sico-qu��mico (coagula����o/flocula����o) os decantadores est��ticos devem possuir o volume ��til de 4,8 m3. Sendo necess��rios semanalmente 36 L da suspens��o de cal (Neutrolac 300) e 12,3 L da solu����o de sulfato de alum��nio a 8,3%. Os tanques de armazenamento destes compostos devem possuir 43,2 litros e 96 litros, respectivamente. Nesta unidade estimou-se que s��o produzidos diariamente 1,4 m3 de lamas. Na unidade de tratamento biol��gico o reactor biol��gico deve possuir um volume ��til de 6 m3. Para que este processo seja eficaz �� necess��rio fornecer diariamente 2,1 kg de oxig��nio. Estima-se que neste processo ser�� necess��rio efectuar a purga de 325 litros de lamas semanalmente. No final da purga rep��e-se o carv��o activado, que poder�� ser arrastado juntamente com as lamas, adicionando-se 100 mg de carv��o por litro de licor misto. De acordo com o volume de lamas produzidos em ambos os tratamentos a ��rea m��nima necess��ria para o leito de secagem �� de cerca de 27 m2. A an��lise econ��mica efectuada mostra que a aquisi����o do equipamento tem o custo de 22.079,50 euros, o custo dos reagentes necess��rios neste processo para um ano de funcionamento tem um custo total de 508,50 euros e as necessidades energ��ticas de 2.008,45 euros.

Estudo da tratabilidade laboratorial e optimiza����o experimental do tratamento de ��guas residuais de ind��strias l��cteas

O presente trabalho experimental teve como objectivos estudar a tratabilidade dum efluente l��cteo utilizando a t��cnica de coagula����o/flocula����o e avaliar a possibilidade de utiliza����o do carv��o activado granulado (CAG) Aquasorb 2000 como adsorvente para a remo����o de compostos org��nicos presentes nos efluentes l��cteos pr�����tratados por coagula����o/flocula����o, funcionando como um tratamento de polimento. No estudo da tratabilidade do efluente por coagula����o/flocula����o investigou-se a influ��ncia de determinadas vari��veis como o tipo e dose de coagulante e pH, a fim de encontrar as melhores condi����es operat��rias. A utiliza����o da referida t��cnica visou a redu����o do valor de concentra����o de alguns par��metros: car��ncia qu��mica de oxig��nio (CQO); f��sforo total e turva����o, tendo sido utilizados efluentes desta ind��stria recolhidos em diferentes datas e ap��s tratamento biol��gico, designados por A, B, C e D apresentando caracter��sticas diferentes. Sendo que o efluente A apresentava valores de CQO, f��sforo total e turva����o de 500 mg O2/L;32 mg P/L e 40 NTU respectivamente, o efluente B 1400 mg O2/L; 120 mg P/L e 80 NTU respectivamente, o efluente C 12300 mg O2/L; 87 mg P/L e 350 NTU respectivamente e o efluente D 340 mg O2/L; 33 mg P/L e 42 NTU respectivamente. Os coagulantes estudados foram hidr��xido de c��lcio (HC), sulfato de alum��nio (SA) e tricloreto de ferro (TF). Verificou-se que o coagulante com maior efic��cia nos efluentes estudados foi o TF. As maiores remo����es de CQO, f��sforo total e turva����o, 89%, 99,9% e 99%, respectivamente, foram obtidas para o efluente C, com uma dosagem de TF de 4 g/L e com um pH entre 6 e 7. Entre os efluentes estudados este era o que apresentava valores iniciais mais elevados para qualquer um destes par��metros. As melhores percentagens de remo����o obtidas com o HC, para a CQO, f��sforo total e turva����o foram de 59%, 99% e 91%, respectivamente, com uma dosagem de HC de 1 g/L e com um pH entre 10 e 11,5 foram conseguidas no tratamento do efluente D, com o qual se alcan��aram tamb��m as melhores remo����es de CQO, f��sforo total e turva����o de 65%, 99% e 87%, respectivamente, quando se utilizou o coagulante SA, com uma dosagem de 2 g/L e com um pH entre 7 e 7,5. Relativamente ao volume de lamas produzido neste processo pela utiliza����o dos diferentes coagulantes no tratamento dos efluentes referidos concluiu-se que o coagulante que gera menor volume de lamas �� o HC, sendo o SA aquele que origina um maior volume. Submeteu-se posteriormente o efluente D, pr��-tratado por coagula����o/flocula����o, a um processo de adsor����o em batch utilizando o CAG Aquasorb 2000, onde se conseguiu uma remo����o de CQO de 48%, alcan��ando para este par��metro o valor de 63 mg O2/L, nas condi����es operat��rias que correspondem a uma massa de CAG de 12,5 g/L e um tempo de contacto de 3 horas. Quanto aos custos associados com os coagulantes, o que menores custos apresenta �� o HC (150 ���/ton), seguido pelo TF (250 ���/ton) e por ultimo o SA (340 ���/ton). Sendo que o efluente quando tratado com TF e SA �� necess��rio uma correc����o do pH do meio para que estes coagulantes actuem eficazmente, em que essa correc����o de pH �� realizada com hidr��xido de s��dio (540 ���/ton). Realizaram-se ainda estudos de equil��brio de adsor����o com o carv��o activado referido e o azul-de-metileno usando diferentes concentra����es deste (50 mg/L; 100 mg/L e 200 mg/L) e diferentes massas de CAG (0,1g; 0,2g; 0,3g; 0,4g e 0,5g). A temperatura a que se realizaram estes ensaios foi de 28,7��C e o volume de azul-de-metileno foi de 200 mL. Verificou-se que os melhores resultados obtidos foram para uma concentra����o de adsorvato de 100 mg/L. Ajustaram-se os modelos de Langmuir e Freundlich ��s isot��rmicas obtidas tendo correla����es mais elevadas para a concentra����o de 100 mg/L de corante (azul de metileno), sendo o modelo de Freundlich aquele que melhor se ajustou apresentando uma correla����o quadr��tica de 0,9744 e os seguintes par��metros Kf = 6,59 e n = 5,33, enquanto que o de Langmuir apresentou uma correla����o quadr��tica de 0,9583 e os seguintes par��metros qm��x = 83,3 mg/g de adsorvente e K = 20 L/mg de adsorvato.. Verificou-se que a capacidade de adsor����o promovida pelo CAG, em rela����o ao azul-demetileno, obtida experimentalmente, 83,3 mg/g, �� muito inferior �� capacidade de adsor����o teoricamente prevista pela ficha t��cnica deste carv��o, 280 mg/g a uma temperatura de 25��C, o que pode indiciar que o carv��o utilizado n��o estaria nas melhores condi����es.

Nephrotoxicity of CCA-treated wood: a comparative study with As2O5 and CrO3 on mice

The purpose of this work was to assess the acute toxicity on male mice to a chromated copper arsenate (CCA) solution, a widespread wood preservative used in building industry until 2002. Animals were subcutaneously injected with CCA (7.2 mg/kg arsenic and 10.2 mg/kg chromium per body weight), CrO3 (10.2 mg/kg), As2O5 (7.2 mg/kg) and NaCl (0.9%) per se, during 48 h and 96 h, for histopathology, histochemistry, chromium and arsenic analysis. The results showed some histopathological changes within renal tubules lumen of CCA exposed animals (during 48 h, and 96 h), and CrO3 (for the period of 96 h). Furthermore, the renal levels of arsenic and chromium in treated animals were statistically more evident than controls. Although, the same contents of pentavalent arsenic and hexavalent chromium were injected into treated animals with CCA and with the prepared solutions of As2O5 and CrO3, a different distribution of the pattern of these compounds was observed in kidneys.

Determination of polyphenols in wines by reaction with 4-aminoantipyrine and photometric flow-injection analysis

A new flow-injection analytical procedure is proposed for the determination of the total amount of polyphenols in wines; the method is based on the formation of a colored complex between 4-aminoantipyrine and phenols, in the presence of an oxidizing reagent. The oxidizing agents hexacyanoferrate(III), peroxodisulfate, and tetroxoiodate(VII) were tested. Batch trials were first performed to select appropriate oxidizing agents, pH, and concentration ratios of reagents, on the basis of their effect on the stability of the colored complex. Conditions selected as a result of these trials were implemented in a flow-injection analytical system in which the influence of injection volume, flow rate, and reaction- coil length, was evaluated. Under the optimum conditions the total amount of polyphenols, expressed as gallic acid, could be determined within a concentration range of 36 to 544 mg L���1, and with a sensitivity of 344 L mol���1 cm���1 and an RSD <1.1%. The reproducibility of analytical readings was indicative of standard deviations <2%. Interference from sugars, tartaric acid, ascorbic acid, methanol, ammonium sulfate, and potassium chloride was negligible. The proposed system was applied to the determination of total polyphenols in red wines, and enabled analysis of approximately 55 samples h���1. Results were usually precise and accurate; the RSD was <3.9% and relative errors, by the Folin���Ciocalteu method, <5.1%.

Agar extraction from integrated multitrophic aquacultured Gracilaria vermiculophylla: Evaluation of a microwave-assisted process using response surface methodology

Microwave-assisted extraction (MAE) of agar from Gracilaria vermiculophylla, produced in an integrated multitrophic aquaculture (IMTA) system, from Ria de Aveiro (northwestern Portugal), was tested and optimized using response surface methodology. The influence of the MAE operational parameters (extraction time, temperature, solvent volume and stirring speed) on the physical and chemical properties of agar (yield, gel strength, gelling and melting temperatures, as well as, sulphate and 3,6-anhydro-Lgalactose contents) was evaluated in a 2^4 orthogonal composite design. The quality of the extracted agar compared favorably with the attained using traditional extraction (2 h at 85��C) while reducing drastically extraction time, solvent consumption and waste disposal requirements. Agar MAE optimum results were: an yield of 14.4 �� 0.4%, a gel strength of 1331 �� 51 g/cm2, 40.7 �� 0.2 _C gelling temperature, 93.1 �� 0.5��C melting temperature, 1.73 �� 0.13% sulfate content and 39.4 �� 0.3% 3,6-anhydro-L-galactose content. Furthermore, this study suggests the feasibility of the exploitation of G. vermiculophylla grew in IMTA systems for agar production.

Clay body wrap with microcurrent: effects in central adiposity

Introduction Increased fat mass is becoming more prevalent in women and its accumulation in the abdominal region can lead to numerous health risks such as diabetes mellitus. The clay body wrap using compounds such as green clay, green tea and magnesium sulfate, in addition to microcurrent, may reduce abdominal fat mass and minimize or prevent numerous health problems. Objective This study aims at measuring the influence of the clay body wrap with microcurrent and aerobic exercise on abdominal fat. Methods Nineteen female patients, randomized into intervention (n = 10) and control (n = 9) groups, were evaluated using ultrasound for visceral and subcutaneous abdominal fat, calipers and abdominal region perimeter for subcutaneous fat and bioimpedance for weight, fat mass percentage and muscular mass. During 10 sessions (5 weeks, twice a week) both groups performed aerobic exercise in a cycloergometer and a clay body wrap with microcurrent was applied to the intervention group. Results When comparing both groups after 5 weeks of protocol, there was a significant decrease in the subcutaneous fat around left anterior superior iliac spine in the intervention group (�� = 0.026 for a confidence interval 95%). When comparing initial and final abdominal fat in the intervention group, measured by ultrasound (subcutaneous and visceral fat) and by skinfold (subcutaneous fat), we detected a significant abdominal fat reduction. Conclusion This study demonstrated that the clay body wrap used with microcurrent and aerobic exercise can have a positive effect on central fat reduction.

Clay body wrap with microcurrent: Effects in central adiposity

Introduction: Increased fat mass is becoming more prevalent in women and its accumulation in the abdominal region can lead to numerous health risks such as diabetes mellitus. The clay body wrap using compounds such as green clay, green tea and magnesium sulfate, in addition to microcurrent, may reduce abdominal fat mass and minimize or prevent numerous health problems. Objective: This study aims at measuring the in���uence of the clay body wrap with microcurrent and aerobic exercise on abdominal fat. Methods: Nineteen female patients, randomized into intervention (n = 10) and control (n = 9) groups, were evaluated using ultrasound for visceral and subcutaneous abdominal fat, calipers and abdominal region perimeter for subcutaneous fat and bioimpedance for weight, fat mass percentage and muscular mass. During 10 sessions (5 weeks, twice a week) both groups performed aerobic exercise in a cycloergometer and a clay body wrap with microcurrent was applied to the intervention group. Results: When comparing both groups after 5 weeks of protocol, there was a signi���cant decrease in the subcutane- ous fat around left anterior superior iliac spine in the intervention group (�� = 0.026 for a con���dence interval 95%). When comparing initial and ���nal abdominal fat in the intervention group, measured by ultrasound (subcutaneous and visceral fat) and by skinfold (subcutaneous fat), we detected a signi���cant abdominal fat reduction. Conclusion: This study demonstrated that the clay body wrap used with microcurrent and aerobic exercise can have a positive effect on central fat reduction.

Desenvolvimento de coagulante/ floculante para tratamento de ��guas residuais numa ind��stria de adesivos

Esta disserta����o teve como objetivo clarificar a qualidade das ��guas residuais de uma ind��stria de fabrica����o de adesivos. Para esta clarifica����o optou-se por um tratamento de coagula����o/flocula����o a ser efetuado com a adi����o de apenas um produto no estado s��lido. Para este estudo, selecionou-se subst��ncias comercialmente dispon��veis destacando-se para esta formula����o um coagulante, sulfato de alum��nio (Al2 (SO4).3H2O, dois adjuvantes, hidr��xido de c��lcio, Ca(OH)2 (adjuvante H) e Montmorillonite, Al2O3.4SiO2.H2O (adjuvante M) e um floculante, uma poliacrilamida ani��nica (C3H5NO)n. O efluente bruto da ind��stria de adesivos foi caraterizado e verificou-se que dos par��metros analisados, apenas o pH obedece aos valores limite de emiss��o para descarga no coletor municipal. Determinaram-se as quantidades ��timas das subst��ncias selecionadas, a quantidade m��nima de produto formulado e foi feita a otimiza����o da composi����o do produto formulado, para tr��s n��veis de pH e duas condi����es de agita����o Numa primeira fase, a realiza����o de ensaios preliminares sobre a quantidade de cada uma das subst��ncias conduziu aos valores 5 e 30 g de coagulante, 2 e 10 g de adjuvante M; 3 g de adjuvante H e 0,01 g de floculante por 500 mL de efluente. Na otimiza����o da quantidade m��nima de produto formulado obteve-se o valor de 5g de produto por 500 mL de efluente. Relativamente �� formula����o do produto foi definido estudar o efeito da varia����o das raz��es, %(m/m), dos adjuvantes (M e H) em fun����o do coagulante, para diferentes valores de pH inicial (6,2; 8,1 e 10) e para duas condi����es de agita����o (A e B), sobre os par��metros analisados (CQO, SST, turva����o, pH final e IVL). Na condi����o A manteve-se uma agita����o de 150 rpm durante 2 minutos, reduzindo-se para 60 rpm durante 15 minutos e, por fim, para 30 rpm durante 5 minutos. Na condi����o B foi usada uma agita����o constante de 90 rpm durante 22 minutos. O estudo do efeito das varia����es das raz��es % (m/m) dos adjuvantes M e H foi dividido em tr��s grupos com tr��s subgrupos: 1�� grupo - 0,6 a raz��o m��ssica adjuvante M/coagulante e 0,4, 1,2 e 2 a raz��o m��ssica adjuvante H/ coagulante; 2�� grupo - 0,2 a raz��o m��ssica adjuvante M/coagulante e 0,1, 0,4 e 0,6 a raz��o m��ssica adjuvante H/ coagulante; 3�� grupo - 0,1 a raz��o m��ssica adjuvante M/coagulante e 0,1, 0,2 e 0,3 a raz��o m��ssica adjuvante H/ coagulante. Ap��s este estudo obteve-se para cada condi����o de agita����o (A e B), as raz��es %(m/m) e o pH inicial mais adequados, com base nos melhores resultados obtidos no efeito sobre a CQO. Para a condi����o de agita����o A o melhor resultado obteve-se para pH inicial igual a 8,1 com a raz��o m��ssica de adjuvante M/ coagulante igual a 0,1 e a raz��o m��ssica de adjuvante H/coagulante igual a 0,1 (percentagens de remo����o de 98,01%, 99,60% e 99,43% para a CQO, SST e turva����o, respetivamente). Para a condi����o de agita����o B o melhor resultado obteve-se para pH inicial igual a 8,1 com a raz��o m��ssica de adjuvante M/ coagulante igual a 0,1 e a raz��o m��ssica de adjuvante H/coagulante igual a 0,1 (percentagens de remo����o de 98,67%, 99,77% e 98,40% para a CQO, SST e turva����o, respetivamente). Nestas condi����es �� necess��rio efetuar a corre����o do pH ap��s o tratamento. Apesar das elevadas percentagens de remo����o obtidas, o ��ndice volum��trico de lamas indica fraca qualidade de sedimenta����o.

Desenvolvimento e aplica����o de um biossensor para monitoriza����o de creatinina, um biomarcador associado a doen��as emergentes

Este trabalho descreve o desenvolvimento de um material sensor para creatinina por impress��o molecular em estrutura polim��rica (MIP) e a sua aplica����o no desenvolvimento de um dispositivo de natureza potenciom��trica para a determina����o da mol��cula alvo em fluidos biol��gicos. A creatinina �� um dos biomarcadores mais utilizados no acompanhamento da doen��a renal, j�� que �� um bom indicador da taxa de filtra����o glomerular (TFG). Os materiais biomim��ticos desenhados para intera����o com a creatinina foram obtidos por polimeriza����o radicalar, recorrendo a mon��meros de ��cido metacr��clico ou de vinilpiridina e a um agente de reticula����o apropriado. De modo a aferir o efeito da impress��o da creatinina na resposta dos materiais MIP �� sua presen��a, foram tamb��m preparados e avaliados materiais de controlo, obtidos sem impress��o molecular (NIP). O controlo da constitui����o qu��mica destes materiais, incluindo a extra����o da mol��cula impressa, foi realizado por Espectroscopia de Raman e de Infravermelho com Transformada de Fourrier. A afinidade de liga����o entre estes materiais e a creatinina foi tamb��m avaliada com base em estudos cin��ticos. Todos os materiais descritos foram integrados em membranas selectivas de el��trodos seletivos de i��o, preparadas sem ou com aditivo i��nico lip��filo, de carga negativa ou positiva. A avalia����o das caracter��sticas gerais de funcionamento destes el��trodos, em meios de composi����o e pH diferentes, indicaram que as membranas com materiais impressos e aditivo ani��nico eram as ��nicas com utilidade anal��tica. Os melhores resultados foram obtidos em solu����o tamp��o Piperazine-N,N���-bis(2- ethanesulfonic acid), PIPES, de pH 2,8, condi����o que permitiu obter uma resposta quasi-Nernstiana, a partir de 1,6��10-5 mol L-1. Estes el��trodos demonstraram ainda uma boa selectividade ao apresentaram uma resposta preferencial para a creatinina quando na presen��a de ureia, carnitina, glucose, ��cido asc��rbico, albumina, cloreto de c��lcio, cloreto de pot��ssio, cloreto de s��dio e sulfato de magn��sio. Os el��trodos foram ainda aplicados com sucesso na an��lise de amostras sint��ticas de urina, quando os materiais sensores eram baseados em ��cido metacrilico, e soro, quando os materiais sensores utilizados eram baseados em vinilpiridina.

New molecularly-imprinted polymer for carnitine and its application as ionophore in potentiometric selective membranes

Carnitine (CRT) is a biological metabolite found in urine that contributes in assessingseveral disease conditions, including cancer. Novel quick screening procedures for CRT are therefore fundamental. This work proposes a novel potentiometric device where molecularly imprinted polymers (MIPs) were used as ionophores. The host-tailored sites were imprinted on a polymeric network assembled by radical polymerization of methacrylic acid (MAA) and trimethylpropane trimethacrylate (TRIM). Non-imprinted polymers (NIPs) were produced as control by removing the template from the reaction media. The selective membrane was prepared by dispersing MIP or NIP particles in plasticizer and poly(vinyl chloride), PVC, and casting this mixture over a solid contact support made of graphite. The composition of the selective membrane was investigated with regard to kind/amount of sensory material (MIP or NIP), and the need for a lipophilic additive. Overall, MIP sensors with additive exhibited the best performance, with near-Nernstian response down to ~ 1 �� 10��� 4 mol L��� 1, at pH 5, and a detection limitof ~ 8 �� 10��� 5 mol L��� 1. Suitable selectivity was found for all membranes, assessed by the matched potential method against some of the most common species in urine (urea, sodium, creatinine, sulfate, fructose and hemoglobin). CRT selective membranes including MIP materials were applied successfully to the potentiometric determination of CRT in urine samples.

Determination of Microcystin-LR in waters in the subnanomolar range by sol���gel imprinted polymers on solid contact electrodes

The present work reports new sensors for the direct determination of Microcystin-LR (MC-LR) in environmental waters. Both selective membrane and solid contact were optimized to ensure suitable analytical features in potentiometric transduction. The sensing layer consisted of Imprinted Sol���Gel (ISG) materials capable of establishing surface interactions with MC-LR. Non-Imprinted Sol���Gel (NISG) membranes were used as negative control. The effects of an ionic lipophilic additive, time of sol���gel polymerization, time of extraction of MC-LR from the sensitive layer, and pH were also studied. The solid contact was made of carbon, aluminium, titanium, copper or nickel/chromium alloys (80 : 20 or 90 : 10). The best ISG sensor had a carbon solid contact and displayed average slopes of 211.3 mV per decade, with detection limits of 7.3 1010 M, corresponding to 0.75 mg L1 . It showed linear responses in the range of 7.7 1010 to 1.9 109 M of MC-LR (corresponding to 0.77���2.00 mg L1 ), thus including the limiting value for MC-LR in waters (1.0 mg L1 ). The potentiometric-selectivity coefficients were assessed by the matched potential method for ionic species regularly found in waters up to their limiting levels. Chloride (Cl) showed limited interference while aluminium (Al3+), ammonium (NH4 + ), magnesium (Mg2+), manganese (Mn2+), sodium (Na+ ), and sulfate (SO4 2) were unable to cause the required potential change. Spiked solutions were tested with the proposed sensor. The relative errors and standard deviation obtained confirmed the accuracy and precision of the method. It also offered the advantages of low cost, portability, easy operation and suitability for adaptation to flow methods.