The analysis of aqueous humor constituents using capillary zone electrophoresis

One of the difficulties encountered in the study of aqueous humor is the relatively small volume generally available for analysis. The purpose of this study was to investigate the potential use of capillary zone electrophoresis (CE) for the analysis of nanolitre quantities of this fluid. Twelve samples of aqueous humor were obtained from patients undergoing cataract surgery and a further three samples were from non cataract post mortem subjects within 6 hr of death. CE was carried out in an uncoated fused silica glass capillary, 75 mu internal diameter and 100 cm long using a run buffer of 40 mM borate pH 9.4 containing 0.4 g l-1 methylcellulose. Detection of the separated zones was by ultra violet absorption at 200 nm. Preliminary identification of peaks was achieved by enzymatic hydrolysis and spiking with purified analytes. A number of very well resolved peaks were obtained from both cataract and post mortem samples using nanolitre quantities of unmodified fluid. Additional peaks were noted in the post mortem samples, most of which were likely to be due to a partial breakdown of the blood aqueous humor barrier. The profiles obtained were not significantly affected by various drugs routinely administered during cataract surgery. This preliminary study has demonstrated the potential value of CE in the analysis of aqueous humor in health and disease.