Analysis and chemical speciation of copper and zinc in wound fluid

A novel method for the analysis of trace element chemical speciation at parts per billion (ppb) levels in wound fluid samples both contributes to the fundamental inorganic biochemistry of the healing process and permits improved treatments. Potentiometric Stripping Analysis in combination with acid digestion has been used to quantify the total copper and zinc levels in a series of 0.5 ml samples of fluid obtained from surgical wounds. Further, the degree of blood contamination has been investigated using visible spectroscopy. The prevailing chemical speciation (chemical forms) of these total concentrations of copper and zinc amongst low molecular mass ligands in wound fluid has been investigated by computer modelling using JESS, the Joint Expert Speciation System. The model, involving 38 components, generates in the region of 3500 individual low molecular mass complexes including copper, zinc, iron, calcium and manganese species, and predicts that the majority of low molecular mass (lmm) copper complexes are electrically net-neutral, whilst those of zinc are predominantly charged. Further studies indicate that supplementing the concentrations of histidine and tryptophan may increase the net-neutral zinc fraction, the optimum effect being achieved at pH=7.4. This may be important in transporting zinc into healing cells.