Derivatized humic acids modified gold electrode: electrochemical characterization and analytical applications

The preparation and application of a humic acids modified gold electrode (HA-CME) have been described. Derivatization of HAs as β-thioesters caused their partial fragmentation and, thus, a consequent separation by size exclusion chromatography (SEC) was necessary. The CME prepared with functionalized HAs having an average MW of 52000 demonstrated to be effective for trace As(III) determination (LOQ = 0.3 μg L −1 ). This CME has been characterized both by electrochemical techniques and atomic force microscopy (AFM). The HA-CME provided reliable measurements in natural waters at different salinity with no need of desalting the sample. Total inorganic arsenic could be determined after reduction of As(V) with SO 2 . Under these conditions, organic arsenic species were not mineralized and did not interfere.