Preparation of Buffer Systems of Constant Ionic Strength

Elving, Philip J.; Markowitz, Joseph M.; Rosenthal, Isadore

doi:10.1021/ac60115a034

Cited by 282 publications

(89 citation statements)

References 13 publications

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“…The resulting crude extract was stored at -80°C. The extraction buffer was a citric acid-phosphate buffer adjusted to constant ionic strength with NaCl (Elving et al 1956). A pH range of 2 to 7.4 was used in reaction assays which were incubated at 30°C in gas-tight vials with 20 mM DMSP added as a substrate.…”

Section: Methodsmentioning

confidence: 99%

Dimethylsulphoniopropionate (DMSP), DMSP-lyase activity (DLA) and dimethylsulphide (DMS) in 10 species of coccolithophore

Franklin¹,

Steinke²,

Young³

et al. 2010

Mar. Ecol. Prog. Ser.

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We investigated dimethylsulphoniopropionate (DMSP) quota (pg DMSP cell -1 ), intracellular DMSP concentration (mM), in vitro and in vivo DMSP-lyase activity (DLA) and dimethylsulphide (DMS) concentration in batch cultures of 10 species of coccolithophore. Species were chosen to span the phylogenetic and size range that exists within the coccolithophores. Our overall objective was to examine if Emiliania huxleyi, considered a 'model' coccolithophore species, is representative in terms of DMSP, DLA and DMS, because other coccolithophores contribute substantially to phytoplankton biomass and carbon fluxes in temperate and tropical waters. DMSP was found in all species, and DMSP quotas correlated significantly with cell volume, reflecting the fundamental physiological role of DMSP as a compatible solute in this group. This DMSP quota-cell volume relationship can be used to calculate the relative contribution of different species to total DMSP. Lowered nutrient availability (batch growth at a 10-fold lower nutrient concentration) did not significantly affect DMSP quota. In contrast to DMSP, DLA and DMS concentration were variable between the subset of species investigated. Coccolithophore DLA is known only in E. huxleyi and Gephyrocapsa oceanica, and we found DLA to be restricted to these closely related species. If DLA is restricted to a subset of coccolithophores, then those species are more likely to emit DMS directly in the sea. Our results indicate that in ecosystems where coccolithophores form stable populations, species other than E. huxleyi can make significant contributions to the particulate DMSP pool and hence to the amount of DMSP potentially available to the microbial loop.KEY WORDS: Marine sulphur cycle · Calcifying haptophytes · Biogeochemistry · Emiliania · Gephyrocapsa · Calcidiscus · Coccolithophores Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 410: [13][14][15][16][17][18][19][20][21][22][23] 2010 the available DMSP being metabolised to sulphate, DMS and methanethiol (Kiene et al. 2000). Due to this bacterial metabolism, which is dependent not just on the species composition of the bacterioplankton, but also on the physiological state of both bacteria and algae, the relationship between microalgal DMSP and DMS release from the oceans is complex and highly variable in space and time (Malin & Kirst 1997). Nevertheless, major factors that govern how much algal DMSP ends up as DMS potentially available for sea-air gas exchange include: (1) the amount of algal DMSP, (2) the activity of algal DMSP-lyase enzymes in DMSP-producing algae, (3) the physiological and photosynthetic state of DMSP producers, (4) the demise of DMSP producers due to natural cell death, grazing and viral lysis, and (5) the composition and metabolic activity of associated bacterioplankton (see Stefels et al. 2007 for review).Knowledge of some of these factors can be gained using laboratory cultures. Emiliania huxleyi is the best studied coccolithophore due to its ubiqui...

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Section: Methodsmentioning

confidence: 99%

Dimethylsulphoniopropionate (DMSP), DMSP-lyase activity (DLA) and dimethylsulphide (DMS) in 10 species of coccolithophore

Franklin¹,

Steinke²,

Young³

et al. 2010

Mar. Ecol. Prog. Ser.

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“…The pH was adjusted with McIlvaine buffer solutions, and the ionic strength controlled to 0.5 mol L -1 with KCl [19]. The metal ions stock solutions were prepared from NiCl 2 .6H 2 O and CoCl 2 .6H 2 O salts (Merck), and standardized by flame atomic absorption.…”

Section: Reagents and Solutionsmentioning

confidence: 99%

Direct and simultaneous spectrophotometric determination of Ni (II) and Co (II) using diethanoldithiocarbamate as complexing agent

et al. 2009

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A direct spectrophotometric method for simultaneous determination of Co(II) and Ni(II), with diethanoldithiocarbamate (DEDC) as complexing agent, is proposed using the maximum absorption at 360 and 638 nm (Co(II)/DEDC) and 390 nm (Ni/DEDC). Adjusting the best metal/ligand ratio, supporting eletrolite, pH, and time of analysis, linear analytical curves from 1.0 10 -6 -4.0 10 -4 for Co(II) in the presence of Ni 1.0 10 -6 -1.0 10 -4 mol L -1 were observed. No further treatment or calculation processes have been necessary. Recoveries in different mixing ratios were of 99%. Interference of Fe(III), Cu(II), Zn(II) and Cd(II), and anions as NO 3 -, Cl -, ClO 4 -, citrate and phosphate has been evaluated. The method was applied to natural waters spiked with the cations.

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“…Foram utilizadas soluções tampão de McIlvaine, preparadas de acordo com Elving et al 24 , para controle de pH na obtenção de espectros de absorção molecular.…”

Section: Reagentes E Soluçõesunclassified

Aplicação de pigmentos de flores no ensino de química

Couto¹,

Ramos²,

Cavalheiro³

1998

Quím. Nova

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Recebido em 17/3/97; aceito em 8/10/97 APPLICATION OF FLOWER PIGMENTS IN CHEMICAL EDUCATION.In the present work, the pH dependent colour change of the crude flower extracts is suggested as subject in teaching chemical or acid-base equilibria, visual indicators and some aspects of spectrophotometric concepts and applications. The vegetal species used are commonly found in Brazil, and the extraction methodology proposed is inexpensive and easy to perform in secondary schools and in general chemistry or instrumental undergraduate courses. A bibliographic review about the use of vegetal extracts in chemical education and a discussion of the flower colour are also presented.Keywords: colour change of crude flower extract; acid-base equilibrium; spectrophotometry. EDUCAÇÃO INTRODUÇÃOAs espécies vegetais, uma vez que não podem se locomover, utilizam-se de artifícios para atrair animais para efetuarem funções tais como a polinização.As flores são utilizadas com esta finalidade, nos vegetais superiores. Por definição botânica as flores são elementos de reprodução de plantas fanerógamas; conjunto de cálice e corola, mais ou menos vistoso, com forma, organização, coloração e demais caracteres extremamente variáveis 1 . A forma, o aroma, o sabor e a coloração de substâncias presentes nas flores são utilizadas para chamar a atenção de mamíferos, insetos e aves.Esta coloração é causada pela presença de pigmentos que absorvem radiação luminosa na região do ultra-violeta e do visível. Estes pigmentos localizam-se nos vacúolos das células vegetais 2 , nos quais o pH varia entre 3,70-4,15 e 4,40-4,50 por exemplo, para o caso de pétalas de rosas, no pico de coloração e após três dias de colhidas, respectivamente, segundo foi relatado por Asen et al 3 . Várias classes de substâncias podem colaborar para a coloração das flores, frutos e folhas dos vegetais, destacando-se as porfirinas, carotenóides e flavonóides 4 . Exemplos destes corantes, bem como seu grupo característico são apresentados na tabela 1.Nas flores os principais agentes cromóforos são os flavonóides. Estes compostos são subdivididos em grupos de substâncias, cada qual apresentando colorações características. Segundo Brouillard 5 , as antocianinas são responsáveis pela coloração rosa, laranja, vermelha, violeta e azul da maioria das flores. Os flavonóis (chalconas e auronas), produzem coloração amarela. Esta mesma cor pode, também, ser produzida por carotenóides.Outros glicosídeos de chalconas, auronas, flavonas e flavonóis podem, também, se apresentar incolores com absorções no ultra-violeta, porém podendo ser vistos por insetos, como as abelhas 5 e possivelmente por pássaros, como os beija-flores.

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Preparation of Buffer Systems of Constant Ionic Strength

Cited by 282 publications

References 13 publications

Dimethylsulphoniopropionate (DMSP), DMSP-lyase activity (DLA) and dimethylsulphide (DMS) in 10 species of coccolithophore

Dimethylsulphoniopropionate (DMSP), DMSP-lyase activity (DLA) and dimethylsulphide (DMS) in 10 species of coccolithophore

Direct and simultaneous spectrophotometric determination of Ni (II) and Co (II) using diethanoldithiocarbamate as complexing agent

Aplicação de pigmentos de flores no ensino de química

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