Determination of Copper in Wine by Anodic Stripping Voltammetry with Rotating Glassy Carbon and Microfiber Carbon Electrode

Anodic stripping voltammetry (ASV) with rotating glassy carbon electrode (RGCE) and microfiber carbon electrode (µFCE), both filmed with mercury, were used to determine copper content in wine. Influence of phenolics on in situ mercury film formation was studied. Wine and quercetin were added gradually into solution of Hg(II) in acetic acid-sodium acetate buffer (pH = 4.60). Reduction of Hg(II) was observed in both cases. In situ filmed electrode was found unsuitable. Results obtained using ex situ filmed RGCE and µFCE were found in good agreement with ASV using hanging mercury drop electrode. Thus, ASV with ex situ mercury filmed electrodes can be recommended for accurate quantification of copper in complex samples containing phenolics, without any special pretreatments. This work is licensed under a Creative Commons Attribution 4.0 International License

Polarografija i voltametrija na živinim elektrodama - nekada, sada i u budućnosti

Dedicated to the memory of Professor Jaroslav Heyrovský on the occasion of 50th Anniversary of Nobel Prize for polarography. History, present status and possible future trends in electroanalytical applications of mercury electrodes, their possibilities and limitation, advantages and disadvantages are discussed on the occasion of the 50th anniversary of Nobel Prize for polarography. For some analytes and some types of matrices, polarographic and Volta metric methods at mercury electrodes are still the 'best method' and can successfully compete with more widespread separation and spectrometric techniques. Lower investment and running costs, high speed, sensitivity, universality, and wide applicability speaks in favor of voltammetric techniques despite their limited selectivity. To increase the use of polarography in modern analytical laboratories it is necessary to improve education in this field and to pay more attention to the validation of newly developed methods. Then polarographic and voltammetric methods at mercury electrodes will play a useful role in electroanalytical chemistry even more than 50 years after Nobel Prize for polarography. .Posvećeno uspomeni na profesora Jaroslava Hejrovskog, povodom pedesetogodišnjice Nobelove nagrade za polarografiju. U tekstu je opisana istorija, današnja uloga i mogućnosti daljeg razvoja primene živinih elektroda u elektroanalitici, njihove mogućnosti i ograničenja, prednosti i nedostaci, a povodom pedesetogodišnjice dodele Nobelove nagrade za hemiju za otkriće i razvoj polarografskih metoda analize. Za neke tipove jedinjenja i matriksaa) polarografija i voltametrija na živinim elektrodama su još uvek 'najbolje metode' koji mogu uspešno da se porede sa primenjivanijim spektrometrijskim tehnikama i metodama odvajanja. Jeftinija oprema i troškovi održavanja, velika brzina, osetljivost, univerzalnost i široka primenjivost idu u prilog voltametrijskim tehnikama, i pored njihove ograničene selektivnosti. Da bi se polarografija više primenjivala u modernim analitičkim laboratorijama neophodno je unaprediti edukaciju u toj oblasti i pokloniti više pažnje validaciji novorazvijenih metoda. Polarografski i voltametrijski metodi na živinoj elektrodi će imati značajnu ulogu u elektroanalitičkoj hemiji, i posle više od pedeset godina od dodele Nobelove nagrade za polarografiju.

Polarografija i voltametrija na živinim elektrodama - nekada, sada i u budućnosti

Dedicated to the memory of Professor Jaroslav Heyrovský on the occasion of 50th Anniversary of Nobel Prize for polarography. History, present status and possible future trends in electroanalytical applications of mercury electrodes, their possibilities and limitation, advantages and disadvantages are discussed on the occasion of the 50th anniversary of Nobel Prize for polarography. For some analytes and some types of matrices, polarographic and Volta metric methods at mercury electrodes are still the 'best method' and can successfully compete with more widespread separation and spectrometric techniques. Lower investment and running costs, high speed, sensitivity, universality, and wide applicability speaks in favor of voltammetric techniques despite their limited selectivity. To increase the use of polarography in modern analytical laboratories it is necessary to improve education in this field and to pay more attention to the validation of newly developed methods. Then polarographic and voltammetric methods at mercury electrodes will play a useful role in electroanalytical chemistry even more than 50 years after Nobel Prize for polarography. .Posvećeno uspomeni na profesora Jaroslava Hejrovskog, povodom pedesetogodišnjice Nobelove nagrade za polarografiju. U tekstu je opisana istorija, današnja uloga i mogućnosti daljeg razvoja primene živinih elektroda u elektroanalitici, njihove mogućnosti i ograničenja, prednosti i nedostaci, a povodom pedesetogodišnjice dodele Nobelove nagrade za hemiju za otkriće i razvoj polarografskih metoda analize. Za neke tipove jedinjenja i matriksaa) polarografija i voltametrija na živinim elektrodama su još uvek 'najbolje metode' koji mogu uspešno da se porede sa primenjivanijim spektrometrijskim tehnikama i metodama odvajanja. Jeftinija oprema i troškovi održavanja, velika brzina, osetljivost, univerzalnost i široka primenjivost idu u prilog voltametrijskim tehnikama, i pored njihove ograničene selektivnosti. Da bi se polarografija više primenjivala u modernim analitičkim laboratorijama neophodno je unaprediti edukaciju u toj oblasti i pokloniti više pažnje validaciji novorazvijenih metoda. Polarografski i voltametrijski metodi na živinoj elektrodi će imati značajnu ulogu u elektroanalitičkoj hemiji, i posle više od pedeset godina od dodele Nobelove nagrade za polarografiju.

Serbian aromatized wine “Bermet”: Electrochemical, chemiluminescent and spectrophotometric determination of antioxidant activity

Serbian aromatized wine “Bermet” from grapes grown on Fruška Gora Mountain has been in production since the 15th century. Ten commercial Bermets produced according to the traditional procedure by different manufacturers, and six prepared within the scope of this study were assessed for antioxidant (AO) activity using electrochemical, chemiluminescent and spectrophotometric AO assays. Direct current polarographic assay based on the decrease of anodic current of [hydrogen(peroxido)(1-)]hydroxidomercury(II) complex formation in alkaline H2O2 solution at potential of mercury oxidation, chemiluminescent H2O2 scavenging assay, as well as commonly used spectrophotometric assays (2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) based Trolox equivalent antioxidant capacity (TEAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP)) were used. Total phenolic content (TPC) was determined by Folin–Ciocalteu assay. The results obtained were correlated using regression analysis, ANOVA and F-test. An integrated approach to AO capacity determination allowed a more comprehensive comparison between samples. The approach is based on the introduction of the relative antioxidant capacity index, calculated by assigning each AO assay equal weight, and by PCA analysis. In addition, the introduction of phenolic antioxidant coefficients, calculated as the ratio between individual AO capacity and TPC, enabled a better understanding of their relation

Antioxidant activity of pea protein hydrolysates produced by batch fermentation with lactic acid bacteria

Nine Lactobacillus strains known for surface proteinase activity were chosen from our collection and tested for their ability to grow in pea seed protein-based medium, and to hydrolyze purified pea proteins in order to produce peptides with antioxidant (AO) activity. Two strains, Lactobacillus rhamnosus BGT10 and Lactobacillus zeae LMG17315, exhibited strong proteolytic activity against pea proteins. The AO activity of the pea hydrolysate fraction, MW lt 10 kDa, obtained by the fermentation of purified pea proteins with Lactobacillus rhamnosus BGT10, was tested by standard spectrophotometric assays (DPPH, ABTS, Fe3+-reducing capacity) and the recently developed direct current (DC) polarographic assay. The low molecular weight fraction of the obtained hydrolysate was separated using ion exchange chromatography, while the AO activity of eluted fractions was determined by means of a sensitive DC polarographic assay without previous concentration of samples. Results revealed that the fraction present in low abundance that contained basic peptides possessed the highest antioxidant activity. Based on the obtained results, it can be concluded that Lactobacillus rhamnosus BGT10 should be further investigated as a candidate strain for large-scale production of bioactive peptides from legume proteins

Udjeli ukupnih fenola, flavan-3-ola i proantocijanidina te oksidacijska stabilnost i antioksidacijski kapacitet čokolade tijekom skladištenja

Antioxidant (AO) capacity of chocolates with 27, 44 and 75 % cocoa was assessed after production and during twelve months of storage by direct current (DC) polarographic assay, based on the decrease of anodic current caused by the formation of hydroxo-perhydroxyl mercury(II) complex (HPMC) in alkaline solutions of hydrogen peroxide at potentials of mercury oxidation, and two spectrophotometric assays. Relative antioxidant capacity index (RACI) was calculated by taking the average value of the AO assay (the sample mass in all assays was identical). Oxidative stability of chocolate fat was determined by differential scanning calorimetry. Measured parameters and RACI were correlated mutually and with the content of total phenols (Folin-Ciocalteu assay), flavan-3-ols (vanillin and p-dimethylaminocinnamaldehyde assay) and proanthocyanidins (modified Bate-Smith assay). During storage, the studied functional and health-related characteristics remained unchanged. Amongst applied AO assays, the DC polarographic one, whose validity was confirmed by two-way ANOVA and F-test, correlated most significantly with oxidative stability (oxidation onset temperature and induction time). In addition, principal component analysis was applied to characterise chocolate types.Antioksidacijski kapacitet čokolade s 27, 44 i 75 % kakaa ispitan je odmah nakon proizvodnje te tijekom dvanaest mjeseci skladištenja, i topolarografskom metodom praćenja smanjenja anodne struje uslijed nastajanja kompleksa žive(II) s hidroksilnim i perhidroksilnim radikalima u alkalnim otopinama vodikovog peroksida pri elektrodnom potencijalu žive, te dvjema spektrofometrijskim metodama. Relativni antioksidacijski kapacitet čokolade izračunat je iz prosječnih rezultata dobivenih pojedinom metodom. Oksidacijska je stabilnost masti u čokoladi određena diferencijalnom pretražnom kalorimetrijom. Dobiveni rezultati uspoređeni su s ukupnim udjelom fenola (određenim pomoću metode Folin-Ciocalteu), flavan-3-ola (određenim pomoću vanilina i p-dimetilaminocinamaldehida) i proantocijanidina (određenim pomoću modificirane Bate-Smith metode). Funkcionalna svojstva i antioksidacijski kapacitet čokolade nisu se mijenjali tijekom skladištenja. Rezultati dobiveni polarografskom metodom uz pomoć jednosmjerne struje, obrađeni dvosmjernim ANOVA testom i F-testom, pokazali su najveću korelaciju s oksidacijskom stabilnosti, tj.temperaturom na kojoj započinje oksidacija i indukcijskim vremenom oksidacije. Analizom glavnih komponenata okarakterizirani su svi uzorci čokolade

Supplementary material for the article: Šoštarić, T. D.; Petrović, M. S.; Pastor, F. T.; Lončarević, D. R.; Petrović, J. T.; Milojković, J. V.; Stojanović, M. D. Study of Heavy Metals Biosorption on Native and Alkali-Treated Apricot Shells and Its Application in Wastewater Treatment. Journal of Molecular Liquids 2018, 259, 340–349. https://doi.org/10.1016/j.molliq.2018.03.055

Supplementary material for: [https://doi.org/10.1016/j.molliq.2018.03.055]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2152]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2970

Primena DP polarografije za određivanje cinka i sadržaja cink-piritiona u šamponima protiv peruti

Commercially formulated anti-dandruff shampoos contain zinc pyrithione (ZPT) as an active ingredient that has antifungal, antibacterial and anti-seborrheic properties. The determination of ZPT concentration in commercial anti-dandruff shampoos by differential pulse polarography (DPP) was based on the electrochemical reduction of zinc ions in ammoniacal buffer pH 10.2, and the linear dependence of the reduction differential pulse peak current at the potential - 1.33 V vs. concentration of zinc. Using the calibration curve method, it was found that the range of linearity for the determination of zinc concentration was from 1.28 x 10-5 to 1.39 x 10-4 mol L‒1 (linear regression equation: I = - 0.097 + 6.635 x 105c). Surface active ingredients and micro-components in the shampoos did not exert a polarographic interference for the determination of zinc and did not affect the indirect determination of the content of the active ingredient ZPT. The concentrations of zinc in the analyzed anti-dandruff shampoo samples were determined by the standard addition method, resulting in 4.20 x 10‒2 mol L‒1, 1.76 x 10‒1 mol L‒1 and 1.82 x 10‒1 mol L‒1. The results of DPP determinations of zinc and ZPT show that the content of ZPT was 0.28%, 1.15% i.e. 1.19% and was below the maximum recommended level of ZPT in anti-dandruff shampoos. This simple and sensitive differential pulse polarography method is suitable for a routine and rapid control of the active ingredient content, as well as for the quality control of anti-dandruff shampoos.Aktivni sastojak komercijalno formulisanih šampona protiv peruti je cink-pirition, koji ima antifungalno, antibakterijsko i antiseboreično dejstvo. Određivanje cink-piritiona u šamponima protiv peruti primenom metode diferencijalne pulsne polarografije zasnivalo se na elektrohemijskoj redukciji jona cinka u amonijačnom puferu pH 10,2 i linearnoj zavisnosti intenziteta struje pika na redukcionom potencijalu - 1,33 V i koncentracije cinka. Metodom kalibracione krive je određen opseg linearnosti za određivanje koncentracije cinka od 1,28 x 10‒5 do 1,39 x 10‒4 mol L-1 i dobijena je linearna regresiona jednačina I = - 0,097 + 6,635 x 105c. Utvrđeno je da površinski aktivne komponente u matriksu šampona ne pokazuju polarografsku interferenciju i ne utiču na određivanje koncentracije cinka i sadržaja cink-piritiona u analiziranim šamponima. Koncentracije cinka u analiziranim uzorcima šampona određene su metodom standardnog dodatka i iznose 4,20 x 10‒2 mol L-1, 1,76 ' 10‒1 mol L-1 i 1,82 x 10‒1 mol L-1. Rezultati polarografskog određivanja cinka i sadržaja cink-piritiona pokazuju da su dobijene vrednosti cink-piritiona 0,28%, 1,15% i 1,19% ispod maksimalno preporučenog sadržaja cink-piritiona u šamponima protiv peruti. Ova jednostavna i osetljiva metoda diferencijalno pulsne polarografije pogodna je za rutinsko i brzo određivanje sadržaja aktivnog sastojka i kontrolu kvaliteta šampona protiv peruti

Food Waste (Beetroot and Apple Pomace) as Sorbent for Lead from Aqueous Solutions—Alternative to Landfill Disposal

This article presents studies, whose main goal was to minimize food waste. To achieve this goal, it is necessary to expand the scope of their application, for example, for the purification of polluted water from heavy metals. Millions of tons of waste from the fruit and vegetable industry, including pomace of apples and beetroots, are thrown into landfills, posing a danger to the environment. In order to solve the problems with the disposal of these wastes, the authors investigated their sorption potential for the removal of lead from wastewater. The sorbents, dried apple (AP), and beetroots (BR) pomaces were characterized by various methods (study of composition, zeta potential, FTIR-ATR, and SEM-EDX). Various models of sorption kinetics and sorption isotherms were analyzed. Kinetical studies under optimal conditions showed that the sorption process occurs through complexation and ion exchange and the determining stage limiting the rate of sorption is the diffusion of lead ions in the sorbent. The maximum sorption capacity was 31.7 and 79.8 mg/g for AP and BR, respectively. The thermodynamic data revealed the spontaneous sorption of lead ions by sorbents. The temperature rise contributes to the sorption increase by the AP sorbent, while for the BR sorbent, the opposite effect is observed. The obtained results showed that apple and beetroots pomaces can serve as effective renewable materials for the preparation of sorbents, contributing to the solution of complex environmental problems

THE APPLICATION OF DP POLAROGRAPHY FOR THE DETERMINATION OF ZINC AND CONTENT OF ZINC PYRITHIONE IN ANTI-DANDRUFF SHAMPOOS

Commercially formulated anti-dandruff shampoos contain zinc pyrithione (ZPT) as an active ingredient that has antifungal, antibacterial and anti-seborrheic properties. The determination of ZPT concentration in commercial anti-dandruff shampoos by differential pulse polarography (DPP) was based on the electrochemical reduction of zinc ions in ammoniacal buffer pH 10.2, and the linear dependence of the reduction differential pulse peak current at the potential - 1.33 V vs. concentration of zinc. Using the calibration curve method, it was found that the range of linearity for the determination of zinc concentration was from 1.28 ´ 10‒5 to 1.39 ´ 10-4 mol L‒1 (linear regression equation: I = - 0.097 + 6.635 ´ 105c). Surface active ingredients and micro-components in the shampoos did not exert a polarographic interference for the determination of zinc and did not affect the indirect determination of the content of the active ingredient ZPT. The concentrations of zinc in the analyzed anti-dandruff shampoo samples were determined by the standard addition method, resulting in 4.20 ´ 10‒2 mol L‒1, 1.76 ´ 10‒1 mol L‒1 and 1.82 ´ 10‒1 mol L‒1. The results of DPP determinations of zinc and ZPT show that the content of ZPT was 0.28%, 1.15% i.e. 1.19% and was below the maximum recommended level of ZPT in anti-dandruff shampoos. This simple and sensitive differential pulse polarography method is suitable for a routine and rapid control of the active ingredient content, as well as for the quality control of anti-dandruff shampoos. PRIMENA DP POLAROGRAFIJE ZA ODREĐIVANJE CINKA I SADRŽAJA CINK-PIRITIONA U ŠAMPONIMA PROTIV PERUTIAktivni sastojak komercijalno formulisanih šampona protiv peruti je cink-pirition, koji ima antifungalno, antibakterijsko i antiseboreično dejstvo. Određivanje cink-piritiona u šamponima protiv peruti primenom metode diferencijalne pulsne polarografije zasnivalo se na elektrohemijskoj redukciji jona cinka u amonijačnom puferu pH 10,2 i linearnoj zavisnosti intenziteta struje pika na redukcionom potencijalu - 1,33 V i koncentracije cinka. Metodom kalibracione krive je određen opseg linearnosti za određivanje koncentracije cinka od 1,28 ´ 10‒5 do 1,39 ´ 10‒4 mol L-1 i dobijena je linearna regresiona jednačina I = - 0,097 + 6,635´105c. Utvrđeno je da površinski aktivne komponente u matriksu šampona ne pokazuju polarografsku interferenciju i ne utiču na određivanje koncentracije cinka i sadržaja cink-piritiona u analiziranim šamponima. Koncentracije cinka u analiziranim uzorcima šampona određene su metodom standardnog dodatka i iznose 4,20 ´ 10‒2 mol L-1, 1,76 ´ 10‒1 mol L-1 i 1,82 ´ 10‒1 mol L-1. Rezultati polarografskog određivanja cinka i sadržaja cink-piritiona pokazuju da su dobijene vrednosti cink-piritiona 0,28%, 1,15% i 1,19% ispod maksimalno preporučenog sadržaja cink-piritiona u šamponima protiv peruti. Ova jednostavna i osetljiva metoda diferencijalno pulsne polarografije pogodna je za rutinsko i brzo određivanje sadržaja aktivnog sastojka i kontrolu kvaliteta šampona protiv peruti. HIGHLIGHTSCommercially formulated anti-dandruff shampoos contain zinc pyrithione (ZPT) as an active ingredient that has antifungal, antibacterial and anti-seborrheic effects;ZPT is based on the organic entity pyrithione (PT) in which a zinc ion forms a metal complex with PT in a 1 : 2 ratio;Determination of ZPT concentration in commercial anti-dandruff shampoos by differential pulse polarography is based on electrochemical reduction of zinc ions in ammoniacal buffer of pH 10.2;Surface active ingredients (anionic and amphoteric) and micro-components in the shampoos do not show a polarographic interference for determination of zinc and do not affect determination of the content of ZPT active ingredient;A simple and sensitive differential pulse polarography method is suitable for routine and rapid control of the active ingredient content, as well as for quality control of anti-dandruff shampoos