Signal-to-noise considerations for rapid scan atomic spectrometry with an inductively coupled plasma

The blank photon flux from an ICP is measured with a conventional 1-m spectrometer for the spectral region from 200 to 450 nm. This flux is then used to calculate the minimum integration time required before quantum noise (shot noise from the photon flux) becomes significant under various conditions. The calculations demonstrate that blank integration times may be much shorter than the times spent integrating either samples or standards without degradation of the total measurement. Comparison to extrapolated values for a high resolution spectrometer configuration indicate that minimum integration times requirements will vary drastically with wavelength, slit width and spectrometer configuration. The data demonstrates that integration times may be as short as l ms under certain circumstances indicating that very rapid scan data acquisition is feasible for ICP-AES if done with intelligent interactive control.