Determination of cadmium in environmental samples by hydride generation with in situ concentration and atomic absorption detection.

A volatile Cd species (presumed to be the hydride) was generated from aqueous solutions by merging sample and tetrahydroborate reductant in a continuous-flow system. The gaseous analyte was transferred onto the inner wall of a graphite tube furnace for in situ preconcentration at 200 degrees C. Calibration was achieved via the method of standard additions. An absolute detection limit (3 sigma blank) of 10 pg was obtained using KBH4 as reductant. The precision of the determination was 12% (RSD) for a Cd concentration of 0.2 ng ml-1 using KBH4. The method was successfully applied to the determination of Cd in several certified environmental reference materials (soil, sediment, sea-water, biological samples) following pressure digestion of the samples by microwave heating in a mixture of acids.