| A speciation tool was developed combining capillary electrophoresis (CE) and inductively coupled plasma mass spectrometry (ICP-MS) to elucidate metal binding patterns with commercial humic substances (HS). Two different interfaces were developed and compared for their efficiency and viability: a direct injection high efficiency nebulizer (DIHEN) and a high efficiency nebulizer (HEN) with a cyclonic spray chamber. A thorough analysis of the migration patterns of commercial HS was established using standard CE with UV absorbance detection. Results comparable to published observations were achieved. The results of the CE/ICP-MS analyses of HS inoculated with Pb lacked a high level of confidence for reproducibility. A mass balance approach was used, and the identity of generalized peak areas was hypothesized. The identity of the various peaks could not be determined with confidence, although it appears that both Pb and HS binding to the separation capillary inhibit the characterization of HS interactions with metal species by CE/ICP-MS. Further analyses are warranted using alternative capillaries, and simpler speciation problems. |
