SEAWATER AS A MULTICOMPONENT PHYSICAL CARRIER FOR ETV-ICP-MS

The beneficence of NASS-3 sea water in enhancing analyte response in ETV-ICP-MS was investigated from a mechanistic viewpoint. Seawater serves as a multi-component physical carrier which acts primarily to increase the transport efficiency of analytes having wide ranging volatilities. A study of the major components of seawater revealed that HCl, released upon the hydrolysis of MgCl2, is most beneficial to very volatile elements (Cd, Rb, Cs and Tl), volatilization of NaCl affects elements of intermediate volatility (Pb, Ag, In, Ga and Bi), and MgO vaporization increases the transport efficiency of involatile elements (Go). Analyte signal enhancements were reduced or signal suppression occurred when NaCl or NASS-3 was added in amounts in excess of 0.07 mu g. The carrier that caused the least signal suppression when used at high concentration was HCl. Decreasing the ETV heating rate enhances the effect of the physical carrier if the matrix element and analyte co-vaporize.