title: Physical and instrumental considerations in the use of lithium phthalocyanine for measurements of the concentration of the oxygen.
abstract: The use of crystals of lithium phthalocyanine (LiPc) to measure the concentration of oxygen in vivo and in vitro by electron paramagnetic resonance leads to experimental constraints due to the very narrow EPR lines that may occur (as narrow as 11-13 mG in the absence of O2), distortions induced by the automatic frequency control system, anisotropy in the spectra (orientation-dependent linewidth is 11-17 mG in the absence of O2), microwave power saturation, and the effect of physiological motion. These constraints can be overcome if recognized. This article highlights the experimental and theoretical basis of these properties of the EPR signal of LiPc and suggests some technical solutions. It is most important to recognize that paramagnetic species such as LiPc present problems that are not commonly encountered in EPR spectroscopy.
authors.affiliation: College of Medicine, Department of Medicine, University of Illinois at Urbana-Champaign 61801.
authors.forename: A I
authors.initials: AI
authors.lastname: Smirnov
authors.forename: S W
authors.initials: SW
authors.lastname: Norby
authors.forename: T
authors.initials: T
authors.lastname: Walczak
authors.forename: K J
authors.initials: KJ
authors.lastname: Liu
authors.forename: H M
authors.initials: HM
authors.lastname: Swartz
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D007211:Indoles; D008280:Magnetics; D009942:Organometallic Compounds; D010100:Oxygen / Q000032:analysis*
chemical_list: D007211:Indoles; D009942:Organometallic Compounds; C081756:lithium phthalocyanine; D010100:Oxygen