Publication detail

Methylation of humic acids – the impact on the reactivity, chemical composition and properties of HAs studied by spectrometric techniques

ENEV, V. KLUČÁKOVÁ, M. SMILEK, J. DOSKOČIL, L.

Original Title

Methylation of humic acids – the impact on the reactivity, chemical composition and properties of HAs studied by spectrometric techniques

Czech Title

Studium vlivu methylace huminových kyselin na jejich reaktivitu, chemické složení a fyzikálně-chemické vlastnosti pomocí spektrometrických technik

English Title

Methylation of humic acids – the impact on the reactivity, chemical composition and properties of HAs studied by spectrometric techniques

Type

abstract

Language

en

Original Abstract

The aim of this work was study chemical composition, chemical properties and reactivity of methylated standard humic acid (mHA) and its native form. Humic acid (standard sample of humic acid – International Humic Substances Society – Leonardite HA 1S104H) was modified by methylation. All samples of Leonardite HAs were characterized by elemental analysis (EA), total organic carbon analysis (TOC), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), steady-state fluorescence spectroscopy and nuclear magnetic resonance (13C NMR). The elemental composition was determined by a CHNS/O Microanalyser Flash 1112 Carlo Erba. Oxygen content was calculated by difference: O % = 100 – (C + H + N + S) %, and data obtained were corrected for moisture and ash content. Absorption coefficients (EET/EBz, E250/E365 and E465/E665) of Leonardite HAs were calculated from the absorbance values. Infrared spectroscopy is a useful technique in characterization of structure, functional groups and formation modes of HAs. For the fluorescence experiments the final concentration of the HAs was adjusted to 10 mg/L. The pH-value of the samples was adjusted to seven using a standard phosphate buffer. Fluorescence mono-dimensional spectra and total luminescence spectra (TLS) of HAs were obtained using steady-state fluorescence spectroscopy. All fluorescence spectra were performed on a Horiba Scientific Fluorolog. Total luminescence spectra (TLS) were obtained in the form of excitation/emission matrix (EEM) by scanning the wavelength emission over the range of 300–600 nm, also the excitation wavelength was in 5 nm steps from 240 to 550 nm. The EEM spectrum of ultrapure water (Mili-Q) was obtained, and it was subtracted from the EEMs of all samples examined to decrease the influence from the 1st- and 2nd-order Raman scattering. Fluorescence index (Milori index and HIX) of HAs was calculated from the area of the emission spectra. The fluorescence intensity (IF) values (in CPS) of samples were corrected using method of Lakowicz1. 13C NMR spectra of Leonardite HAs were obtained with a Bruker Avance III NMR spectrometer at an observation frequency of 125.8 MHz for 13C. The approximate number of scans was 25.000. Aromaticity (fa), hydrophilicity and hydrophobicity ratio (Hfi/Hfo) and biological activity (BiA) of HAs were calculated from the area of the NMR spectra.

Czech abstract

Předložená práce se zabývá studiem chemického složení, chemických vlastností a reaktivity methylovaného standardu huminové kyseliny (mHK) a její nativní formy. Huminová kyselina (Leonardite HK 1S104H) dodávaná společností International Humic Substances Society (IHSS) byla modifikována methylací karboxylových a fenolických funkčních skupin. Všechny vzorky standardu HK byly charakterizovány pomocí elementární analýzy (EA) se zaměřením na obsah biogenních prvků (C, H, N, S, O, P), celkového obsahu organického uhlíku (TOC), UV/Vis spektrometrie, infračervené spektrometrie s Fourierovou transformací, "steady-state" fluorescenční spektrometrie a "liquid state" 13C spektrometrie nukleární magnetické resonance (13C NMR). Elementární složení vzorků HK bylo získáno pomocí elementárního analyzátoru CHNS/O Microanalyser Flash 1112 Carlo Erba. Množství kyslíku HK bylo vypočteno jako rozdíl z experimentálně zjištěných hodnot obsahu uhlíku, vodíku, dusíku a síry: O % = 100 – (C + H + N + S) %. Tyto hodnoty byly následně korigovány z důvodu jistého obsahu vlhkosti a popelovin (tj. nespalitelného podílu ve vzorku) v HK. Absorpční koeficienty (EET/EBz, E250/E365 a E465/E665) methylované a nativní HK byly vypočteny z příslušných hodnot absorbancí naměřených UV/Vis spekter. Infračervená spektrometrie byla využita k charakterizaci struktury a funkčních skupin (–OCH3) příslušných vzorků HK. Roztoky vzorků byly připraveny o koncentraci 10 mg/dm3 ve standardním fosfátovém pufru (Na2HPO4 a NaH2PO4) při hodnotě pH 7. Mono-dimensionální a excitačně-emisní fluorescenční spektra vzorků HK byly získány pomocí "steady-state" fluorescenční spektrometrie. Všechny fluorescenční spektra byly měřeny na luminiscenčním spektrofotometru Horiba Scientific Fluorolog. Fluorescenční indexy (HIX – humifikační index a Milori index) huminových kyselin byly vypočteny z jejich naměřených emisních spekter. Hodnoty fluorescenčních intenzit – IF (CPS) byly korigovány podle Lakowicze pro odstranění filtračních efektů roztoků huminových látek. Všechny vzorky HK byly měřeny na 13C NMR spektrofotometru Bruker Avance III při frekvenci 125,8 MHz. Celkový počet skenů pro získání kvalitativních a kvantitativních 13C NMR spekter vzorků HK byl optimalizován na 25 000. 13C NMR spektra byla rozdělena na čtyři základní oblasti: oblast alifatických atomů C (0–45 ppm), oblast O-alkylových a peptidových C atomů (45–106 ppm), aromatických a fenolických uhlíků (106–165 ppm) a karboxylových a karbonylových atomů C (165–220 ppm). 13C NMR parametry (fa – parametr aromaticity, Hfi/Hfo – poměr hydrofilnosti a hydrofobnosti, BiA – parametr biologické aktivity) HK byly vypočteny z jejich naměřených 13C NMR spekter.

English abstract

The aim of this work was study chemical composition, chemical properties and reactivity of methylated standard humic acid (mHA) and its native form. Humic acid (standard sample of humic acid – International Humic Substances Society – Leonardite HA 1S104H) was modified by methylation. All samples of Leonardite HAs were characterized by elemental analysis (EA), total organic carbon analysis (TOC), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), steady-state fluorescence spectroscopy and nuclear magnetic resonance (13C NMR). The elemental composition was determined by a CHNS/O Microanalyser Flash 1112 Carlo Erba. Oxygen content was calculated by difference: O % = 100 – (C + H + N + S) %, and data obtained were corrected for moisture and ash content. Absorption coefficients (EET/EBz, E250/E365 and E465/E665) of Leonardite HAs were calculated from the absorbance values. Infrared spectroscopy is a useful technique in characterization of structure, functional groups and formation modes of HAs. For the fluorescence experiments the final concentration of the HAs was adjusted to 10 mg/L. The pH-value of the samples was adjusted to seven using a standard phosphate buffer. Fluorescence mono-dimensional spectra and total luminescence spectra (TLS) of HAs were obtained using steady-state fluorescence spectroscopy. All fluorescence spectra were performed on a Horiba Scientific Fluorolog. Total luminescence spectra (TLS) were obtained in the form of excitation/emission matrix (EEM) by scanning the wavelength emission over the range of 300–600 nm, also the excitation wavelength was in 5 nm steps from 240 to 550 nm. The EEM spectrum of ultrapure water (Mili-Q) was obtained, and it was subtracted from the EEMs of all samples examined to decrease the influence from the 1st- and 2nd-order Raman scattering. Fluorescence index (Milori index and HIX) of HAs was calculated from the area of the emission spectra. The fluorescence intensity (IF) values (in CPS) of samples were corrected using method of Lakowicz1. 13C NMR spectra of Leonardite HAs were obtained with a Bruker Avance III NMR spectrometer at an observation frequency of 125.8 MHz for 13C. The approximate number of scans was 25.000. Aromaticity (fa), hydrophilicity and hydrophobicity ratio (Hfi/Hfo) and biological activity (BiA) of HAs were calculated from the area of the NMR spectra.

Keywords

humic acids, methylation, methyl esters, elemental analysis, UV/Vis, FTIR, 13C NMR and fluorescence spectroscopy, NMR parameters, aromaticity, hydrophilicity and hydrophobicity ratio, biological activity

Released

08.06.2015

Publisher

European Colloid & Interface Society

Location

Kraków, Poland, EU

Pages from

111

Pages to

111

Pages count

1

BibTex


@misc{BUT114924,
  author="Vojtěch {Enev} and Martina {Klučáková} and Jiří {Smilek} and Leoš {Doskočil}",
  title="Methylation of humic acids – the impact on the reactivity, chemical composition and properties of HAs studied by spectrometric techniques",
  annote="The aim of this work was study chemical composition, chemical properties and reactivity of methylated standard humic acid (mHA) and its native form. Humic acid (standard sample of humic acid – International Humic Substances Society – Leonardite HA 1S104H) was modified by methylation. All samples of Leonardite HAs were characterized by elemental analysis (EA), total organic carbon analysis (TOC), ultraviolet-visible spectroscopy (UV/Vis), Fourier transform infrared spectroscopy (FTIR), steady-state fluorescence spectroscopy and nuclear magnetic resonance (13C NMR). The elemental composition was determined by a CHNS/O Microanalyser Flash 1112 Carlo Erba. Oxygen content was calculated by difference: O % = 100 – (C + H + N + S) %, and data obtained were corrected for moisture and ash content. Absorption coefficients (EET/EBz, E250/E365 and E465/E665) of Leonardite HAs were calculated from the absorbance values. Infrared spectroscopy is a useful technique in characterization of structure, functional groups and formation modes of HAs. For the fluorescence experiments the final concentration of the HAs was adjusted to 10 mg/L. The pH-value of the samples was adjusted to seven using a standard phosphate buffer. Fluorescence mono-dimensional spectra and total luminescence spectra (TLS) of HAs were obtained using steady-state fluorescence spectroscopy. All fluorescence spectra were performed on a Horiba Scientific Fluorolog. Total luminescence spectra (TLS) were obtained in the form of excitation/emission matrix (EEM) by scanning the wavelength emission over the range of 300–600 nm, also the excitation wavelength was in 5 nm steps from 240 to 550 nm. The EEM spectrum of ultrapure water (Mili-Q) was obtained, and it was subtracted from the EEMs of all samples examined to decrease the influence from the 1st- and 2nd-order Raman scattering. Fluorescence index (Milori index and HIX) of HAs was calculated from the area of the emission spectra. The fluorescence intensity (IF) values (in CPS) of samples were corrected using method of Lakowicz1. 13C NMR spectra of Leonardite HAs were obtained with a Bruker Avance III NMR spectrometer at an observation frequency of 125.8 MHz for 13C. The approximate number of scans was 25.000. Aromaticity (fa), hydrophilicity and hydrophobicity ratio (Hfi/Hfo) and biological activity (BiA) of HAs were calculated from the area of the NMR spectra.",
  address="European Colloid & Interface Society",
  booktitle="15th European Student Colloid Conference – Book of abstract",
  chapter="114924",
  howpublished="electronic, physical medium",
  institution="European Colloid & Interface Society",
  year="2015",
  month="june",
  pages="111--111",
  publisher="European Colloid & Interface Society",
  type="abstract"
}