Pub Date : 2018-01-29DOI: 10.1590/S0100-46702009000300003
H. Behmadi, Seyed Mahdi Saadati, M. Roshani, M. Ghaemy
A series of novel disulfonamide derivatives were synthesized and characterized by FT-IR, 1H NMR and MS techniques. In order to prepare new disulfonamides, at first we synthesized new diamines containing a pyridine ring. Then, they have been reacted with sulfonyl chlorides to give corresponding disulfonamides.
{"title":"Synthesis of new disulfonamides from different substituted diamino pyridines","authors":"H. Behmadi, Seyed Mahdi Saadati, M. Roshani, M. Ghaemy","doi":"10.1590/S0100-46702009000300003","DOIUrl":"https://doi.org/10.1590/S0100-46702009000300003","url":null,"abstract":"A series of novel disulfonamide derivatives were synthesized and characterized by FT-IR, 1H NMR and MS techniques. In order to prepare new disulfonamides, at first we synthesized new diamines containing a pyridine ring. Then, they have been reacted with sulfonyl chlorides to give corresponding disulfonamides.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"27-31"},"PeriodicalIF":0.0,"publicationDate":"2018-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1590/S0100-46702009000300003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45290366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-24DOI: 10.1590/S0100-46702009000200003
R. A. Sousa, É. Cavalheiro
A potentiometric titration method for the determination of minoxidil based on its re- dox reaction with K2Cr2O7 is described. The best results were observed using 1.00 x 10-3 mol L-1 K2Cr2O7 and 1.00 x 10-2 mol L-1 minoxidil solutions, and the minoxidil as titrant in 2.00 mol L-1 H2SO4 medium. The method was applied to commercial samples and compared with the results from a chromatographic procedure. Recoveries from 97.4 to 98.7 % were observed depending on the sample. Comparison with the chromatographic procedure reveled agreement within 90% confidence level.
基于米诺地尔与K2Cr2O7的还原反应，建立了测定米诺地尔的电位滴定法。使用1.00 x 10-3 mol L-1 K2Cr2O7和1.00 x 10-2 mol L-1的米诺地尔溶液，以及米诺地尔作为滴定剂在2.00 mol L-1H2SO4介质中观察到最佳结果。该方法应用于商业样品，并与色谱程序的结果进行了比较。根据样品的不同，回收率为97.4%至98.7%。与色谱程序的比较表明，在90%的置信水平内一致。
{"title":"Potentiometric determination of Minoxidil in topical use pharmaceutical samples","authors":"R. A. Sousa, É. Cavalheiro","doi":"10.1590/S0100-46702009000200003","DOIUrl":"https://doi.org/10.1590/S0100-46702009000200003","url":null,"abstract":"A potentiometric titration method for the determination of minoxidil based on its re- dox reaction with K2Cr2O7 is described. The best results were observed using 1.00 x 10-3 mol L-1 K2Cr2O7 and 1.00 x 10-2 mol L-1 minoxidil solutions, and the minoxidil as titrant in 2.00 mol L-1 H2SO4 medium. The method was applied to commercial samples and compared with the results from a chromatographic procedure. Recoveries from 97.4 to 98.7 % were observed depending on the sample. Comparison with the chromatographic procedure reveled agreement within 90% confidence level.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"23-27"},"PeriodicalIF":0.0,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1590/S0100-46702009000200003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45518114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-24DOI: 10.1590/S0100-46702009000200005
V. Visani, Sara Regina Ribeiro Carneiro de Barros, Heronides Adonias Dantas Filho, L. F. Almeida, R. Lima, W. Fragoso, T. C. Saldanha, M. C. U. Araújo
The application of multivariate calibration techniques to multicomponent analysis by UV-VIS molecular absorption spectrometry is a powerful tool for simul- taneous determination of several chemical species. However, when this methodol- ogy is accomplished manually, it is slow and laborious, consumes high amounts of reagents and samples, is susceptible to contaminations and presents a high opera- tional cost. To overcome these drawbacks, a flow-batch analyser is proposed in this work. This analyser was developed for automatic preparation of standard calibration and test (or validation) mixtures. It was applied to the simultaneous determination of Cu 2+ , Mn 2+ and Zn 2+ in polyvitaminic and polymineral pharmaceutical formula- tions, using 4-(2-piridilazo) resorcinol as reagent and a UV-VIS spectrophotometer with a photodiode array detector. The results obtained with the proposed system are in good agreement with those obtained by flame atomic absorption spectrometry, which was employed as reference method. With the proposed analyser, the prepara- tion of calibration and test mixtures can be accomplished about four hours, while the manual procedure requires at least two days. Moreover, it consumes smaller amounts of reagents and samples than the manual procedure. After the preparation of calibration and test mixtures, 60 samples h -1 can be carried out with the proposed flow-batch analyser.
{"title":"Flow-batch analyser for preparation of calibration standard mixtures in simultaneous multicomponent spectrometric analysis","authors":"V. Visani, Sara Regina Ribeiro Carneiro de Barros, Heronides Adonias Dantas Filho, L. F. Almeida, R. Lima, W. Fragoso, T. C. Saldanha, M. C. U. Araújo","doi":"10.1590/S0100-46702009000200005","DOIUrl":"https://doi.org/10.1590/S0100-46702009000200005","url":null,"abstract":"The application of multivariate calibration techniques to multicomponent analysis by UV-VIS molecular absorption spectrometry is a powerful tool for simul- taneous determination of several chemical species. However, when this methodol- ogy is accomplished manually, it is slow and laborious, consumes high amounts of reagents and samples, is susceptible to contaminations and presents a high opera- tional cost. To overcome these drawbacks, a flow-batch analyser is proposed in this work. This analyser was developed for automatic preparation of standard calibration and test (or validation) mixtures. It was applied to the simultaneous determination of Cu 2+ , Mn 2+ and Zn 2+ in polyvitaminic and polymineral pharmaceutical formula- tions, using 4-(2-piridilazo) resorcinol as reagent and a UV-VIS spectrophotometer with a photodiode array detector. The results obtained with the proposed system are in good agreement with those obtained by flame atomic absorption spectrometry, which was employed as reference method. With the proposed analyser, the prepara- tion of calibration and test mixtures can be accomplished about four hours, while the manual procedure requires at least two days. Moreover, it consumes smaller amounts of reagents and samples than the manual procedure. After the preparation of calibration and test mixtures, 60 samples h -1 can be carried out with the proposed flow-batch analyser.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"37-47"},"PeriodicalIF":0.0,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45394713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-24DOI: 10.1590/S0100-46702009000200008
O. Fatibello‐Filho, H. Vieira
A spectrophotometric flow injection method for the determination of Zn(II) in ophthalmic formulations was developed. In this work, Zn(II) ion was complexed with Alizarin red S in borate buffer solution (pH 9.0) and the chromophore produced was monitored at 520 nm. The analytical curve was linear in the Zn(II) concentration range from 6.05 x 10-6 to 1.50 x 10-4 mol L-1 with a detection limit of 3.60 x 10-6 mol L-1. Recoveries ranged from 96.3 to 105 % and a relative standard deviation of 1.2 % (n = 10) for 5.5x10-5 mol L-1 Zn(II) reference solution were obtained. The sampling rate was 60 h-1 and the results obtained of Zn(II) in ophthalmic products using this procedure are in close agreement with those obtained using a comparative spectrophotometric procedure at 95 % confidence level.
建立了流动注射分光光度法测定眼用制剂中锌的方法。在本工作中，Zn（II）离子与茜素红S在硼酸盐缓冲溶液（pH 9.0）中络合，并在520nm处监测产生的发色团。分析曲线在锌（II）浓度范围为6.05 x 10-6至1.50 x 10-4 mol L-1时呈线性，检测限为3.60 x 10-6 mol L-1。回收率为96.3至105%，5.5x10-5 mol L-1 Zn（II）对照溶液的相对标准偏差为1.2%（n=10）。采样率为60h-1，使用该方法获得的眼科产品中Zn（II）的结果与使用95%置信水平的比较分光光度法获得的结果非常一致。
{"title":"Spectrophotometric flow injection system for determination of Zn2+ in ophthalmic formulations using Alizarin red S","authors":"O. Fatibello‐Filho, H. Vieira","doi":"10.1590/S0100-46702009000200008","DOIUrl":"https://doi.org/10.1590/S0100-46702009000200008","url":null,"abstract":"A spectrophotometric flow injection method for the determination of Zn(II) in ophthalmic formulations was developed. In this work, Zn(II) ion was complexed with Alizarin red S in borate buffer solution (pH 9.0) and the chromophore produced was monitored at 520 nm. The analytical curve was linear in the Zn(II) concentration range from 6.05 x 10-6 to 1.50 x 10-4 mol L-1 with a detection limit of 3.60 x 10-6 mol L-1. Recoveries ranged from 96.3 to 105 % and a relative standard deviation of 1.2 % (n = 10) for 5.5x10-5 mol L-1 Zn(II) reference solution were obtained. The sampling rate was 60 h-1 and the results obtained of Zn(II) in ophthalmic products using this procedure are in close agreement with those obtained using a comparative spectrophotometric procedure at 95 % confidence level.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"67-72"},"PeriodicalIF":0.0,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1590/S0100-46702009000200008","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45817810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-24DOI: 10.1590/S0100-46702009000200004
M. Tubino, C. Queiroz
Flow injection (FI) methodology, using diffuse reflectance in the visible region of the spectrum, for the analysis of total sulfur in the form of sulfate, precipitated in the form of barium sulfate, is presented. The method was applied to biodiesel, to plant leaves and to natural waters analysis. The analytical signal (S) correlates linearly with sulfate concentration (C) between 20 and 120 ppm, through the equation S= 1 .138+0.0934 C (r = 0.9993). The expe- rimentally observed limit of detection is about 10 ppm. The mean R.S.D. is about 3.0 %. Real samples containing sulfate were analyzed and the results obtained by the FI and by the referen- ce batch turbidimetric method using the statistical Student's t-test and F-test were compared.
{"title":"Flow injection visible diffuse reflectance quantitative analysis of total sulfur in biodiesel, in plant leaves and in natural waters","authors":"M. Tubino, C. Queiroz","doi":"10.1590/S0100-46702009000200004","DOIUrl":"https://doi.org/10.1590/S0100-46702009000200004","url":null,"abstract":"Flow injection (FI) methodology, using diffuse reflectance in the visible region of the spectrum, for the analysis of total sulfur in the form of sulfate, precipitated in the form of barium sulfate, is presented. The method was applied to biodiesel, to plant leaves and to natural waters analysis. The analytical signal (S) correlates linearly with sulfate concentration (C) between 20 and 120 ppm, through the equation S= 1 .138+0.0934 C (r = 0.9993). The expe- rimentally observed limit of detection is about 10 ppm. The mean R.S.D. is about 3.0 %. Real samples containing sulfate were analyzed and the results obtained by the FI and by the referen- ce batch turbidimetric method using the statistical Student's t-test and F-test were compared.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"29-36"},"PeriodicalIF":0.0,"publicationDate":"2018-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47590828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-23DOI: 10.1590/S0100-46702009000100008
C. Branco, A. L. Silva, J. Luiz, L. P. Mercuri, J. R. Matos
Ten samples of kidney stone had been studied through elemental analysis of CHN (EA), Infrared Absorption Spectroscopy and X-Ray Powder Diffraction (XRD). The thermal behavior of the samples is studied by Thermogravimetry/Derivative Thermogravimetry (TG/DTG) and Differential Scanning Calorimetry (DSC). The results of AE, IV absorption Spectroscopy and XRD showed the presence of struvite (NH4Mg [PO4].6H2O), apatite, monohydrated calcium oxalate and dihydrated calcium oxalate. The TG and DSC curves allowed to classify the samples in two different groups: Group I show typical thermal behavior of struvite and Group II present a profile thermal analytical characteristic of a mixture of calcium oxalate.
{"title":"Caracterização de cálculos renais por análise térmica","authors":"C. Branco, A. L. Silva, J. Luiz, L. P. Mercuri, J. R. Matos","doi":"10.1590/S0100-46702009000100008","DOIUrl":"https://doi.org/10.1590/S0100-46702009000100008","url":null,"abstract":"Ten samples of kidney stone had been studied through elemental analysis of CHN (EA), Infrared Absorption Spectroscopy and X-Ray Powder Diffraction (XRD). The thermal behavior of the samples is studied by Thermogravimetry/Derivative Thermogravimetry (TG/DTG) and Differential Scanning Calorimetry (DSC). The results of AE, IV absorption Spectroscopy and XRD showed the presence of struvite (NH4Mg [PO4].6H2O), apatite, monohydrated calcium oxalate and dihydrated calcium oxalate. The TG and DSC curves allowed to classify the samples in two different groups: Group I show typical thermal behavior of struvite and Group II present a profile thermal analytical characteristic of a mixture of calcium oxalate.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"51-56"},"PeriodicalIF":0.0,"publicationDate":"2018-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44260400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-23DOI: 10.1590/S0100-46702009000100004
B. Cristóvão, W. Ferenc, J. Sarzyński, H. Głuchowska
The physico-chemical properties of the new 3d-4f heteronuclear complexes with general formula LnCu3(C11H8N2 O4Br)3·13H2O (where Ln = Pr, Eu, Gd, Tb, Er, Yb and H3(C11H8N2 O4Br) - 5-bromosalicylideneglycylglycine) were studied. The compounds were characterized by elemental, spectral and thermal analyses and magnetic measurements. The formation of Schiff base is evidenced by a strong band at ca. 1646-1650 cm-1 attributable to C=N stretching mode. The presence of water molecules is confirmed by broad absorptions with maximum at 3360 - 3368 cm-1. The Cu(II)-Ln(III) complexes are stable up to ca. 318 K. During dehydration process the water molecules are lost probably in two stages. The magnetic susceptibility data for these complexes change with temperature according to the Curie-Weiss law.
{"title":"Synthesis and magnetic studies of copper(II)-lanthanide(III) 5-bromosalicylideneglycylglycine","authors":"B. Cristóvão, W. Ferenc, J. Sarzyński, H. Głuchowska","doi":"10.1590/S0100-46702009000100004","DOIUrl":"https://doi.org/10.1590/S0100-46702009000100004","url":null,"abstract":"The physico-chemical properties of the new 3d-4f heteronuclear complexes with general formula LnCu3(C11H8N2 O4Br)3·13H2O (where Ln = Pr, Eu, Gd, Tb, Er, Yb and H3(C11H8N2 O4Br) - 5-bromosalicylideneglycylglycine) were studied. The compounds were characterized by elemental, spectral and thermal analyses and magnetic measurements. The formation of Schiff base is evidenced by a strong band at ca. 1646-1650 cm-1 attributable to C=N stretching mode. The presence of water molecules is confirmed by broad absorptions with maximum at 3360 - 3368 cm-1. The Cu(II)-Ln(III) complexes are stable up to ca. 318 K. During dehydration process the water molecules are lost probably in two stages. The magnetic susceptibility data for these complexes change with temperature according to the Curie-Weiss law.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"25-30"},"PeriodicalIF":0.0,"publicationDate":"2018-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1590/S0100-46702009000100004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42731567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-23DOI: 10.1590/S0100-46702009000100010
A. Dziewulska-KuBaczkowska, W. Ferenc
The complexes of silver(I) with 2,3-, 2,4-, 2,6-, 3,4-, 3,5-dimethoxy-, and 2,3,4- and 3,4,5-trimethoxybenzoic acid anions have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric and X-ray studies. Their solubility in water has been also determined at 293K. All analysed complexes were found to be crystalline, anhydrous compounds with low symmetry. The carboxylate groups act as bidentate or monodentate ligands. The thermal stability of compounds has been examined in air in temperature range of 293-1173K. The analysed complexes were found to be stable at room temperature and their solubilities in water at 293K to be in the order of 10-4 mol.dm-3.
{"title":"Thermal and spectral properties of di-and trimethoxybenzoates of silver (I)","authors":"A. Dziewulska-KuBaczkowska, W. Ferenc","doi":"10.1590/S0100-46702009000100010","DOIUrl":"https://doi.org/10.1590/S0100-46702009000100010","url":null,"abstract":"The complexes of silver(I) with 2,3-, 2,4-, 2,6-, 3,4-, 3,5-dimethoxy-, and 2,3,4- and 3,4,5-trimethoxybenzoic acid anions have been synthesized and characterized by elemental analysis, IR spectroscopy, thermogravimetric and X-ray studies. Their solubility in water has been also determined at 293K. All analysed complexes were found to be crystalline, anhydrous compounds with low symmetry. The carboxylate groups act as bidentate or monodentate ligands. The thermal stability of compounds has been examined in air in temperature range of 293-1173K. The analysed complexes were found to be stable at room temperature and their solubilities in water at 293K to be in the order of 10-4 mol.dm-3.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"63-66"},"PeriodicalIF":0.0,"publicationDate":"2018-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42061256","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-23DOI: 10.1590/S0100-46702009000100007
D. A. Fungaro, J. C. Izidoro, M. Bruno
Coal fly ashes treated by hydrothermal method were used as low-cost adsorbent for the removal of metals ions and dye from aqueous solution. The adsorption isotherms of the treated fly ashes were studied and results were fitted using Langmuir and Freundlich models. It shows that the Freundlich isotherm is better in describing the adsorption process for methylene blue. The equilibrium data for zinc and cadmium ions adsorption well fitted to the Langmuir equation. The maximum adsorption capacity value obtained was 0.78 (mg g-1)(L mg)1/n for methylene blue, 38.05 mg g-1 for Zn2+ and 67.48 mg g-1 for Cd2+. The synthesized materials exhibit much higher adsorption capacities than raw fly ashes. The study showed that the zeolitic material can effectively adsorb methylene blue and metals ions with removal efficiencies ranging from 82-99%.
{"title":"Aplicação de material zeolítico sintetizado de cinzas de carvão como adsorvente de poluentes em água","authors":"D. A. Fungaro, J. C. Izidoro, M. Bruno","doi":"10.1590/S0100-46702009000100007","DOIUrl":"https://doi.org/10.1590/S0100-46702009000100007","url":null,"abstract":"Coal fly ashes treated by hydrothermal method were used as low-cost adsorbent for the removal of metals ions and dye from aqueous solution. The adsorption isotherms of the treated fly ashes were studied and results were fitted using Langmuir and Freundlich models. It shows that the Freundlich isotherm is better in describing the adsorption process for methylene blue. The equilibrium data for zinc and cadmium ions adsorption well fitted to the Langmuir equation. The maximum adsorption capacity value obtained was 0.78 (mg g-1)(L mg)1/n for methylene blue, 38.05 mg g-1 for Zn2+ and 67.48 mg g-1 for Cd2+. The synthesized materials exhibit much higher adsorption capacities than raw fly ashes. The study showed that the zeolitic material can effectively adsorb methylene blue and metals ions with removal efficiencies ranging from 82-99%.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"34 1","pages":"45-50"},"PeriodicalIF":0.0,"publicationDate":"2018-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49174717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2018-01-22DOI: 10.1590/S0100-46702010000400019
D. Vaz, A. Fernandes, B. Szpoganicz, M. M. D. Sierra
In this study the BEST7 software was employed to quantify different classes of functional groups and to model the proton titration behavior of humic substances. To illustrate the process, the Suwannee River fulvic acid of the IHSS (International Humic Substances Society) was used. Five categories - two classes of phenolic groups (phenol and cathecol), two classes of carboxylic groups (benzoic and phtalic) and the combination between them (salicylic) - of oxygenated groups were considered as being responsible for the potentiometric behavior of the sample and were quantitatively determined. The most and the least abundant groups were cathecol (3.300 ± 0.010 mmol g-1) and phenol (1.225 ± 0.070 mmol g-1), respectively. The estimated equilibrium constants were also determined and were in good agreement with the literature values for phenol and cathecol groups and for benzoic, phtalic and salicylic acids. Distribution diagrams of the species were generated with the software SPE and SPEPLOT.
{"title":"Potentiometric quantification and speciation of oxygenated groups in humic substances using BEST7 software","authors":"D. Vaz, A. Fernandes, B. Szpoganicz, M. M. D. Sierra","doi":"10.1590/S0100-46702010000400019","DOIUrl":"https://doi.org/10.1590/S0100-46702010000400019","url":null,"abstract":"In this study the BEST7 software was employed to quantify different classes of functional groups and to model the proton titration behavior of humic substances. To illustrate the process, the Suwannee River fulvic acid of the IHSS (International Humic Substances Society) was used. Five categories - two classes of phenolic groups (phenol and cathecol), two classes of carboxylic groups (benzoic and phtalic) and the combination between them (salicylic) - of oxygenated groups were considered as being responsible for the potentiometric behavior of the sample and were quantitatively determined. The most and the least abundant groups were cathecol (3.300 ± 0.010 mmol g-1) and phenol (1.225 ± 0.070 mmol g-1), respectively. The estimated equilibrium constants were also determined and were in good agreement with the literature values for phenol and cathecol groups and for benzoic, phtalic and salicylic acids. Distribution diagrams of the species were generated with the software SPE and SPEPLOT.","PeriodicalId":35894,"journal":{"name":"Ecletica Quimica","volume":"35 1","pages":"147-152"},"PeriodicalIF":0.0,"publicationDate":"2018-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41635654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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