Speciation Studies of Biologically Active Compounds (Atomic Absorption, Ultrasonic Nebulization, Hplc, Organoleads, Aminoglycosides-Metal Complexes).

Abstract

Part I. Development of a new nebulizer-flame atomizer atomic absorption system designed for metal speciation. A new flame atomic absorption system has been designed and developed. A new, highly efficient ultrasonic nebulizer was used for sample introduction and aerosol generation. Extensive evaluations and modifications of commercially available atomic absorption spray chambers and burner heads were conducted. Observations made during these studies centered on some of the fundamental properties of aerosol transport within the atomic absorption nebulization system. The new flame atomic absorption system consisted of the ultrasonic nebulizer incorporated into a modified spray chamber. The aerodynamic properties of the chamber were designed to given maximal aerosol transport. Burner extensions were incorporated into the chamber and could be resistively heated to aid in desolvation of the aerosol. This system exhibited an increase in sensitivity, depending on the conditions and flow rates, of approximately 5 to 7 fold, and an increase in detection limits of approximately 2 to 4 fold over that reported for commercial flame atomizers. Part II. The speciation of organoleads, mercury compounds, and metal complexes of aminoglycosides. A number of physiologically and environmentally important organoleads and mercurials were speciated by high performance liquid chromatography-atomic absorption (HPLC-AA). HPLC systems were developed to separate these compounds by using complementary thin layer chromatographic (TLC) methods with colorimetry detection. These systems were used to study the conversion of tetraethyllead in seawater over a long period of time and the decomposition of diethyllead dichloride. Results showed that the triethyllead chloride was stable in seawater for at least one year, and that diethyllead chloride decomposes into triethyllead chloride and lead(2+) compounds. Metal complexation with a class antibiotics, aminoglycosides, was investigated both by HPLC-AA and TLC-colorimetry. New HPLC and TLC systems were developed to separate the metal/complexes or the uncomplexed aminoglycoside. The formation of the copper and cobalt complexes was shown to be a function of the ratio of metal to aminoglycoside.