量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Reproducibility of the X-band EPR measurement of an aqueous solution sample was compared using three different types of sample tubes, and accuracy of quantitative performance was assessed. A PTEE tubing, a glass capillary and a quartz flat cuvette were compared to get a suitable condition for quantitative measurement. An accurate 0.1 mM water solution of TEMPOL was used as a standard sample. The TEMPOL solution was loaded into one of sample tube, and the sample tube was set in the TE-mode cavity of X-band EPR spectrometer. Two procedures below were tested for reproducibility of repeated measurements. 1) The sample tube in the cavity was washed or renewed every measurement, and measurements were repeated several times with fixed EPR parameters. 2) The sample tubes in the cavity were stayed and repeatedly measured several times. Next, EPR parameters such as sweep speed, time constant, modulation width, and/or microwave power were varied to seek optimum signal intensity. The PTFE tubing showed the best reproducibility when the measurements were repeated with staying the sample tube (the ratio of standard deviation to the averaged signal intensity; SD/AV = 0.0058). When the sample and sample tube was renewed every measurement, variation of signal intensity became larger (SD/AV = 0.0333). The glass capillary had the best reproducibility in both procedures 1 and 2 (SD/AV = 0.0104 and 0.0036, respectively). The signal reproducibility of the flat cuvette was relatively low (SD/AV = 0.0400 and 0.0690 for procedures 1 and 2, respectively). However, the flat cuvette gave the largest signal intensity when the loaded volume of the sample was the identical. In conclusion, the best quantitative performance of the X-band EPR spectroscopy for a liquid sample was obtained when the measurements are carried out with the capillary.
Comparison of Sample Tubes for the X-band EPR Measurement of an Aqueous Sample: Effects on Reproducibility of Signal Intensities
