Solid phase extraction of aldosterone and analysis using amperometric detection

Abstract

A method has been investigated to detect aldosterone in serum and urine using solid phase extraction, high performance liquid chromatography, and amperometric detection. The procedure circumvents the hazards and disposal expense of the radioisotopic waste generated by the use of radioimmunoassay, and the large amounts of organic solvents necessary for liquid-liquid extraction ofthe hormone by classical methods of analysis. Random first morning urine samples were acid hydrolysed, and serum was untreated. Aldosterone was successfully recovered from spiked samples using cyclohexyl solid phase extraction in a procedure that was inexpensive, rapid, and easy. Separation of the aldosterone from interferences was accomplished using HPLC on a reversed phase (C18) column. Detection was accomplished using a thin-layer electrochemical cell via the redox reaction of copper (I) bis-phenathroline, following the reduction of the copper (II) form of this complex by the aldehyde functional group of aldosterone in a heated postcolumn reactor bath. This method proved to be very specific for the separation of aldosterone from interferences in complex biological matrices.