Electron paramagnetic resonance (EPR) was used for the determination of semiquinone-type radical content of HAs. The spectra of the four HAs were obtained with a Bruker ELEXSYS-E500 spectrometer equipped with an NMR teslameter (ER 036TM) at room temperature. X-band spectra were collected using a Bruker ER 4105DR double resonator dedicated to quantitative studies and operating in the TE104 mode with a nominal center frequency of 9.7 GHz. During measurements, the standard was held in one cavity while the sample was held in the second cavity, so during measurements, both cavities had identical conditions. The standard was an IHSS Leonardite HA of known weight that was permanently embedded in a quartz tube. The semiquinone radical concentration of the Leonardite standard was measured using a Bruker alanine pill standard. Two measurements were made for each HA using different subsamples.
Er 036tm
Manufactured by Bruker
The ER 036TM is a high-performance benchtop electron paramagnetic resonance (EPR) spectrometer manufactured by Bruker. It is designed to provide reliable and accurate measurements of electron spin resonance in a wide range of samples, including solids, liquids, and gases. The ER 036TM is a versatile instrument that can be used in various fields, including chemistry, physics, and materials science.
Automatically generated - may contain errors
Lab products found in correlation
E 41 fc, by Bruker (2 mentions)
Elexsys e500, by Bruker (2 mentions)
Elexsys e500 spectrometer, by Bruker (1 mentions)
E580 spectrometer, by Bruker (1 mentions)
Matlab software, by MathWorks (1 mentions)
Elexsys e500 cw epr spectrometer, by Bruker (1 mentions)
Winepr simfonia program, by Bruker (1 mentions)
Superconducting magnet, by Oxford Instruments (1 mentions)
Mpms xl 5 squid magnetometer, by Quantum Design (1 mentions)
E500 cw epr spectrometer, by Bruker (1 mentions)
6 protocols using er 036tm
1
Semiquinone Radical Content Analysis of Humic Acids by EPR
2
EPR Spectroscopy of Protein Samples
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The EPR spectra were recorded on a Bruker E-580 spectrometer in the continuous wave mode operating at 9.38 GHz. An Oxford liquid helium flow cryostat was used for cryogenic measurements at 5 K. The measurements were carried out at an incident microwave power of 1.2 milliwatt with a field modulation of 0.5 mT at 100 kHz. The microwave frequency was monitored by a frequency counter (Bruker SuperX-FT bridge), and the magnetic flux density was determined by a teslameter (Bruker ER 036TM). The sample concentration was about 1 mM in 50 mM Tris, 500 mM NaCl, pH 7.5. To quantitatively analyze the EPR signals, MATLAB software (Mathworks, USA) and EasySpin34 (link) were utilized and the detailed procedure for the quantification of the EPR signals and simulation of the EPR spectra are described in Supplementary Information .
3
EPR Spectroscopy of Peptide-Metal Complexes
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EPR spectra were recorded using
a Bruker ELEXSYS E500 CW-EPR spectrometer equipped with an NMR teslameter
(ER 036TM) and a frequency counter (E 41 FC) at X-band frequency,
at 77 K and room temperature. The peptide concentration was 1 mM,
and the metal:ligand molar ratio 1:1.1. The solution for EPR experiments
was prepared using ethylene glycol (5%) as a cryoprotectant. EPR parameters
were obtained by using the Bruker WinEPR SimFonia program and Doublet
new (EPR OF S = 1/2) program
by A. Ozarowski (National High Field Magnetic Laboratory, University
of Florida, Gainesville, FL).
a Bruker ELEXSYS E500 CW-EPR spectrometer equipped with an NMR teslameter
(ER 036TM) and a frequency counter (E 41 FC) at X-band frequency,
at 77 K and room temperature. The peptide concentration was 1 mM,
and the metal:ligand molar ratio 1:1.1. The solution for EPR experiments
was prepared using ethylene glycol (5%) as a cryoprotectant. EPR parameters
were obtained by using the Bruker WinEPR SimFonia program and Doublet
new (EPR OF S = 1/2) program
by A. Ozarowski (National High Field Magnetic Laboratory, University
of Florida, Gainesville, FL).
4
Quantification of Radical Spins in Lichen Samples
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Before EPR analysis, a 2-mm section of the edge of each dried lichen sample was cut using a clean ceramic put into a glass tube. The EPR spectra were then recorded, at room temperature, using a Bruker Elexsys E500 spectrometer operating at X-band, equipped with a NMR teslameter (ER 036TM) and a frequency meter. For quantitative measurements, a standard of known spin concentration (Leonardite humic acid, prepared and distributed by IHSS) was placed in the first cavity of the double resonator and the sample in the second one. After tuning, the measurement parameters were set, the EPR spectra were recorded separately for each cavity (i.e., one for the standard and one for the sample. The analysis of the radical quantity (by double integration within the same magnetic field region), in the studied sample and in the Leonardite standard, was carried out using the Bruker WinEPR Processing software, version V2.22Rev.12.
5
Magnetic Susceptibility and High-Field EPR Characterization
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Magnetic susceptibility measurements over the temperature range 1.8-300 K were performed at a magnetic field of 0.5 T using a Quantum Design SQUID MPMSXL-5 magnetometer.
Correction for the sample holder, as well as the diamagnetic correction χ D , which was estimated from the Pascal constants, 22 was applied.
High-field, high-frequency EPR spectra at temperatures ranging from ca. 3 K to 290 K were recorded on a home-built spectrometer at the EMR facility of the NHMFL 23 with the microwave frequencies 52-416 GHz. The instrument is a transmission-type device and uses no resonance cavity. The microwaves were generated by a phase-locked Virginia Diodes source, generating frequency of 13 ± 1 GHz, and equipped with a cascade of frequency multipliers to generate higher harmonic frequencies. A superconducting magnet (Oxford Instruments) capable of reaching a field of 17 T was employed. Additionally, X-band and Q-Band spectra were recorded on a Bruker ElexSys E500 instrument equipped with an NMR teslameter ER 036TM and a frequency counter E 41 FC (Faculty of Chemistry, Wroclaw University).
Correction for the sample holder, as well as the diamagnetic correction χ D , which was estimated from the Pascal constants, 22 was applied.
High-field, high-frequency EPR spectra at temperatures ranging from ca. 3 K to 290 K were recorded on a home-built spectrometer at the EMR facility of the NHMFL 23 with the microwave frequencies 52-416 GHz. The instrument is a transmission-type device and uses no resonance cavity. The microwaves were generated by a phase-locked Virginia Diodes source, generating frequency of 13 ± 1 GHz, and equipped with a cascade of frequency multipliers to generate higher harmonic frequencies. A superconducting magnet (Oxford Instruments) capable of reaching a field of 17 T was employed. Additionally, X-band and Q-Band spectra were recorded on a Bruker ElexSys E500 instrument equipped with an NMR teslameter ER 036TM and a frequency counter E 41 FC (Faculty of Chemistry, Wroclaw University).
6
EPR Spectroscopy of Complexes at 77K
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Spectra were recorded on a Bruker ELEXSYS E500 CW-EPR spectrometer equipped with an NMR teslameter (ER 036TM) and a frequency counter at X-band frequency and at 77 K. The concentrations of the complexes were 1 mM. The solutions were prepared using water and ethylene glycol (30 v/v%) as a cryoprotectant. The EPR parameters were calculated for the spectra obtained at the maximum concentration of the particular species for which well-resolved components were observed.
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