Study of the chelation of boron with Azomethine H by differential pulse polarography, liquid chromatography and capillary electrophoresis and its analytical applications

Boron chelates with Azomethine H; this forms the basis of a spectrophotometric method for boron determination at 410 nm. An attempt to use differential pulse polarography to decrease the limit of detection (LOD) of this method by separation of the signals due to the free ligand and the chelate was unsuccessful. Liquid chromatography using an ion pair of the anionic chelate with cations such as cetyltrimethylammonium bromide (CTAB) also proved unsuccessful in the reversed mode since the overall ion pair was still negatively charged due to the boron centre of the chelate. Capillary electrophoresis in the reverse polarity mode could separate the chelate from Azomethine H. The LOD could be lowered from 5 X 10(-7) mol dm(-3) to 5 X 10(-8) mol dm(-3) using the stacking technique with diethylenetriamine (DETA). Capillary electrophoresis is shown to be selective for boron determination in an artificial river water matrix with 100% signal recovery and a LOD of 15 ng ml(-1) boron.