Studies are presented describing an application of the NaBH4 reduction of soluble arsenite to form arsine for ultra-trace level arsenic determination by capacitively coupled microwave plasma atomic emission spectrometry. The arsine was condensed in a liquid nitrogen cooled trap, and introduced into the plasma after the elimination of reaction by-products that would reduce the excitation efficiency of the plasma. Use of a photodiode array detector provided a means of background correction. The procedure resulted in a limit of detection of 110 pg and linear dynamic range of 104 for arsenic.
Hueber, D. M., Masamba, W. R. L., Spencer, B. M., & Winefordner, J. D. (1993). Application of hydride generation to the determination of trace concentrations of arsenic by capacitively coupled microwave plasma. Analytica Chimica Acta, 278(2), 279-285. https://doi.org/10.1016/0003-2670