USE OF SIGNAL-TO-ROOT BACKGROUND RATIO AS THE OPTIMIZATION PARAMETER FOR INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROSCOPY WITH CHARGED-COUPLED DEVICE DETECTION

The use of the signal-to-root background ratio (SRBR) of a spectral li ne as the measurable parameter chosen as the criterion for single-elem ent optimization of an inductively coupled plasma with charge-coupled device detection is described. The theoretical background to the choic e of the SRBR, rather than the more usual signal-to-background ratio ( SER), is given. Single-element optimization of the carrier gas how rat e and viewing height using both atomic and ionic lines from ten elemen ts is described. The improvement in the detection limit by using the S RBR over the SBR varies by a factor of 1.0-4.8. For example, the detec tion limit for the Mn II emission line at 257.610 nm is improved from 13.4 ng ml(-1) by SBR optimization to 2.8 ng ml(-1) by maximizing the SRBR.