A Sensitive Method for Determination of Contaminants in Ground

Abstract

There are various methods available for determination of inorganic contaminants existing in ground, but none of them satisfies the requirements, namely, rapidity, inexpensiveness and high performance of analysis, from a standpoint of environmental geotechnics. Analytical methods are primarily required to be simple in treatment, but an analytical instrumentation developed recently needs a skill in operating them and strict maintenance control, resulting in an increased instrumentation and running cost of analysis.
A novel analytical method for determination of inorganic ions contained in contaminated soil has been developed. Chemiluminescence (CL) emerges when a chemical species receives activation energy in a chemical reaction system and then the activated species reacts with other substances or alternate stable species. Thus a great difference between fluorescence (FL) and CL is observed in the transition process from the ground state to an excited state. However, the reversed transition process from the excited state to the ground state is the same for both FL and CL. Luminol is known as the most famous and popular synthetic reagent to generate CL, because it has a large quantum yield. The intensity of luminol oxidation CL is increased by a catalyst like heavy metal as added to the system, and the degree of the enhanced intensity is proportional to the concentration of the catalyst. Inorganic ions able to catalyze the luminol CL reaction can therefore be determined by the CL detection.
The CL analysis using luminol as a CL reagent has many merits for determination of inorganic ions. A wide working range, high sensitivity, low detection limits, rapid analysis, easy operation and low cost are the features characterizing the method. The method was applied to detect contaminants accompanying the stabilization of ground samples. As a result, inorganic anions like silicate which is difficult to determine by other present methods could be determined easily. The chemical principle and analytical utility of this method, especially for anions, are presented.