PERFORMANCE OF A NOVEL SILICA T-TUBE INTERFACE FOR THE AAS DETECTION OF ARSENIC AND SELENIUM-COMPOUNDS IN HPLC COLUMN ELUATE

An improved interface design for the on-line AAS detection of arsenic and selenium compounds in HPLC column eluate is described. Analyte contained in either an aqueous or a polar organic mobile phase is combusted in the hydrogen/oxygen atmosphere of a heated pyrolysis chamber contained within an expanded section of the lower portion of the fused silica T-tube device. Products are entrained into an unheated optical tube by the expanding gases. The interface provides approximately equivalent responses to different analyte-element oxidation states which result in low to subnanogram chromatographic limits of detection for As oxyanions, arsonium cations, Se anions and Se amino acids in an aqueous or methanolic mobile phase. Nascent As anions and As cations are conveniently coextracted from aqueous solution or from fish muscle by phenol extraction and quantified in the same chromatographic run. This method was applied to a standard reference sample of freeze-dried dogfish muscle.