Use of ultrasonic baths for analytical applications: a new approach for optimisation conditions

Nascentes, Clésia C.; Korn, Mauro; Sousa, Clarivaldo Santos de; Arruda, Marco Aurélio Zezzi

doi:10.1590/s0103-50532001000100008

Cited by 91 publications

(46 citation statements)

References 22 publications

(33 reference statements)

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“…Vessels were kept in the central position of the bath for all samples and water was periodically changed to keep the temperature around 25-30 °C. These conditions are compatible with those established by Nascentes et al 27 As expected, sulfur and selenium are mainly contained in the protein fraction. Previous study has shown that selenium is covalently bond to proteins by methionine and cysteine amino acids.…”

Section: Fractionation Of Barium Based On Chemical Compositionsupporting

confidence: 92%

Determination and fractionation of barium in Brazil nuts

Gonçalves

Fernandes

Ramos

et al. 2009

J. Braz. Chem. Soc.

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, respectivamente. Esses resultados indicaram a indisponibilidade de bário presente nesse alimento ao organismo humano. Baseando-se nos teores de bário e enxofre nas diferentes frações e em cálculos estequiométricos para as possíveis reações envolvidas pode-se inferir que bário se encontra principalmente na forma de BaSO 4 . Experimentos termogravimétricos também confirmaram essa suposição.Several sample preparation strategies were employed for determination and fractionation of barium in Brazil nuts using measurements by graphite furnace atomic absorption spectrometry (GF AAS) and inductively coupled plasma optical emission spectrometry with axial view (ICP OES). This food is widely consumed because of its nutritional value and good taste. The chemical analysis of Brazil nuts is not trivial due to their complex matrix. The fractionation of barium in Brazil nuts was studied owing to the toxicity of this element and the strong correlation between chemical form and absorption. Total concentrations of barium varied from 860 to 2084 mg kg -1 . Sequential extractions were performed based on solubility in different media and also according to lipids, proteins and low molecular weight fractions (LMW). The greatest contents of barium were determined in the LMW and in the water insoluble fractions with concentrations in the range 778 to 1606 and 551 to 1520 mg kg -1 , respectively. Based on these results it can be inferred that Ba is not absorbed when Brazil nuts are ingested. Considering both the contents of barium and sulfur in different fractions and stoichiometric calculations it was also possible to assume that barium occurs mainly in the BaSO 4 form. The presence of this chemical form was also confirmed by thermogravimetric measurements.

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Section: Fractionation Of Barium Based On Chemical Compositionsupporting

confidence: 92%

Determination and fractionation of barium in Brazil nuts

Gonçalves

Fernandes

Ramos

et al. 2009

J. Braz. Chem. Soc.

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“…The reaction vial was placed in the maximum energy area in the cleaner. 44 Water was added or removed in order to control the bath temperature.…”

Section: Methodsmentioning

confidence: 99%

Utilization of ultrasonic irradiation as green and effective one-pot protocol to prepare novel series of bis-2-amino-1,3,4-oxa(thia)diazoles and bis-tetrazoles

Arafa¹,

Abdel‐Magied²

2017

Arkivoc

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In an effective and straightforward conversion, bis-semicarbazones and bis-thiosemicarbazones are transformed into a diversity of novel substituted bis-2-amino-1,3,4-oxadiazoles and bis-2-amino-1,3,4-thiadiazoles, respectively under ultrasonic irradiation. Bis-tetrazoles are obtained from the dialdehydes by sequential reaction with hydroxylamine hydrochloride, phosphorus pentoxide and sodium azide without isolation of the intermediates oximes and nitriles. All the reactions proceed cleanly and smoothly under mild conditions, with short reaction times and broad functional groups possibility. No side reactions were observed.

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“…Soc. incidence and maintaining the level of the solution in the sonoreactor equal to the water level in the ultrasonic bath. 10 The temperature during sonication was maintained at 15±1 o C with a Tecnal TE184 thermostatic bath (Piracicaba, Brazil).…”

Section: Apparatusmentioning

confidence: 99%

Production of chloride and hypochlorite for analytical purposes by sonochemical degradation of organochlorines

Korn¹,

Acevedo²,

Borges³

et al. 2005

J. Braz. Chem. Soc.

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Neste trabalho foram enfatizadas as potencialidades da geração sonoquímica de reagentes pela irradiação ultra-sônica de resíduos de organoclorados de efluentes laboratoriais com a produção de soluções de cloreto e hipoclorito para propósitos analíticos. Foi avaliada a dependência entre a produção de cloreto obtida pela sonicação de efluentes contendo organoclorados e o tempo de irradiação para CCl 4 , CHCl 3 , CH 2 Cl 2 e do inseticida Thiamethoxam ® . Sob condições de saturação pôde ser observada a maior produção de cloreto para CHCl 3 . O processo sonoquímico de geração de cloreto mostrou boa precisão (RSD < 10%). A extensão da geração sonoquímica de hipoclorito foi também avaliada quando conduzida em presença de concentrações diferentes de NaOH. O hipoclorito gerado pela degradação de resíduos foi monitorado pelo método de Berthelot, empregado para a determinação de NH 4 + . Os resultados da produção de azul de indofenol obtidos com soluções de hipoclorito geradas sonoquimicamente foram comparados, para diferentes concentrações de NH 4 + , com solução comercial do reagente e nenhuma diferença significativa (nível de confiança de 95%) foi constatada.This work was aimed at highlighting the potentialities of the reagent generation by ultrasonic irradiation to produce chloride and hypochlorite solutions for analytical purposes derived from the residues of organochlorines of laboratory effluents. The dependence between the production of chloride obtained from the sonication of effluents containing organochlorines and the irradiation time was evaluated for CCl 4 , CHCl 3 , CH 2 Cl 2 and Thiamethoxam ® . It was observed that under saturation conditions the production of chloride was highest for CHCl 3 . Additionally, good precision related to the sonochemical generation of chloride was achieved (RSD < 10%). The extent of sonochemical generation of hypochlorite was also evaluated in the presence of different NaOH concentrations. The hypochlorite generated by the degradation of CCl 4 residues was monitored by the reference Berthelot method for NH 4 + determination. The results obtained with hypochlorite solution sonochemically generated for different NH 4 + concentration were compared with the conventional reagent and no significant difference (95% confidence level) was found.

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Use of ultrasonic baths for analytical applications: a new approach for optimisation conditions

Cited by 91 publications

References 22 publications

Determination and fractionation of barium in Brazil nuts

Determination and fractionation of barium in Brazil nuts

Utilization of ultrasonic irradiation as green and effective one-pot protocol to prepare novel series of bis-2-amino-1,3,4-oxa(thia)diazoles and bis-tetrazoles

Production of chloride and hypochlorite for analytical purposes by sonochemical degradation of organochlorines

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