Determination of the coordination environment of Cu(II) in human hair and its possible relevance to health and hair care treatments
This paper addresses the question of the coordination environment of copper (II) in hair.
The research is based on electron paramagnetic resonance (EPR), a spectroscopic technique that detects specifically paramagnetic molecules. Samples were investigated from various male and female subjects of different ages and races.
The Cu(II) EPR signals seemed to be a combination of two components in widely differing relative proportions, although both have the relationship g// > g⊥ > 2.0 expected for the unpaired electron in a orbital and are thus consistent with square planar or tetragonal symmetry for the Cu(II) ion. With a very few samples, the EPR spectra consisted of a single component, and high quality spectra from these samples are presented for use as standard reference results. In one type of complex, 14N superhyperfine structure (shfs) was resolved and the spectrum corresponds to Cu coordination to mixed O‐ and N‐containing functional groups, although the number of N atoms cannot be determined with certainty. No 14N shfs was seen in the spectrum from the other type of complex, and its narrow linewidth excluded the possibility of any. Furthermore, the spectral parameters are inconsistent with coordination of the Cu to four O atoms, but consistent with some S coordinated to the Cu. Large variations between the relative proportions of the two Cu(II) forms were observed with a single healthy subject over a 5‐year period, thus suggesting that they are determined by ‘environmental’ factors, possibly hair treatment processes, rather than being markers for the health of the subject.
EPR spectroscopy is a convenient non‐destructive method for determining the Cu coordination environment in hair, and could be used to monitor its response to various types of hair treatment.
No Supplementary Data
No Article Media
Document Type: Research Article
Publication date: October 1, 2013