TY - JOUR
T1 - Simplifying quantitative measurement of free radical species using an X-band EPR spectrometer
AU - Makino, Yusuke
AU - Ueno, Megumi
AU - Shoji, Yoshimi
AU - Nyui, Minako
AU - Nakanishi, Ikuo
AU - Fukui, Koji
AU - Matsumoto, Ken Ichiro
N1 - Funding Information:
The authors thank Dr. Murali C. Krishna at the National Cancer Institute, NIH (Bethesda, MD) for instructing us in X-band EPR measurement using PTFE tubing as a sample tube. The authors gratefully acknowledge Ms. Masayo Terada for assisting office management of QRSG and QRCG. Part of this study was supported by JSPS KAKENHI Grant Number 18K07739 and 21K07634.
Publisher Copyright:
© 2022 The Society for Free Radical Research Japan. All rights reserved.
PY - 2022
Y1 - 2022
N2 - The quantitative measurement of free radicals in liquid using an X-band electron paramagnetic resonance (EPR) was systematized. Quantification of free radicals by EPR requires a standard sample that contains a known spin amount/concentration. When satisfactory reproducibility of the sample material, volume, shape, and positioning in the cavity for EPR measurements can be guaranteed, a sample tested and a standard can be directly compared and the process of quantification can be simplified. The purpose of this study was to simplify manual quantitative EPR measurement. A suitable sample volume for achieving a stable EPR intensity was estimated. The effects of different solvents on the EPR sensitivity were compared. The stability and reproducibility of the EPR intensity of standard nitroxyl radical solutions were compared among different types of sample tubes. When the sample tubes, sample volumes, and/or solvents were the same, the EPR intensity was reproduced with an error of 2% or less for μM samples. The quantified sample and the standard sample in the same solvent and the same volume drawn into the same sample tube was able to be directly compared. The standard sample for quantification should be measured just before or after every daily experiment.
AB - The quantitative measurement of free radicals in liquid using an X-band electron paramagnetic resonance (EPR) was systematized. Quantification of free radicals by EPR requires a standard sample that contains a known spin amount/concentration. When satisfactory reproducibility of the sample material, volume, shape, and positioning in the cavity for EPR measurements can be guaranteed, a sample tested and a standard can be directly compared and the process of quantification can be simplified. The purpose of this study was to simplify manual quantitative EPR measurement. A suitable sample volume for achieving a stable EPR intensity was estimated. The effects of different solvents on the EPR sensitivity were compared. The stability and reproducibility of the EPR intensity of standard nitroxyl radical solutions were compared among different types of sample tubes. When the sample tubes, sample volumes, and/or solvents were the same, the EPR intensity was reproduced with an error of 2% or less for μM samples. The quantified sample and the standard sample in the same solvent and the same volume drawn into the same sample tube was able to be directly compared. The standard sample for quantification should be measured just before or after every daily experiment.
KW - electron paramagnetic resonance
KW - quantitative measurement
KW - reproducibility
KW - sample tube
KW - sensitivity
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U2 - 10.3164/jcbn.21-83
DO - 10.3164/jcbn.21-83
M3 - Article
AN - SCOPUS:85131206401
SN - 0912-0009
VL - 70
SP - 213
EP - 221
JO - Journal of Clinical Biochemistry and Nutrition
JF - Journal of Clinical Biochemistry and Nutrition
IS - 3
ER -