Evaluation of a Commercially Available Laser-Scanning Microdensitometer for Emission Spectrographic Measurements

The photographic emulsion is one of the oldest detectors used in atomic emission spectroscopy. Although overshadowed by modern electronic detectors for quantitative measurements, there remain significant advantages in their use for qualitative spectroscopic studies. Relative to direct reader and electronic image detector (i.e., photodiode array and charge-coupled device) simultaneous multichannel measurement schemes, photographic emulsions provide considerably greater detection flexibility for qualitative analytical determinations. Their large physical size and low cost allow simultaneous measurements with resolution and wavelength coverages that are not attainable with any other system (and at a cost that any research program can afford). Admittedly, the nonlinear response of the photographic emulsion to emission intensity requires the use of complex calibration schemes for quantitation, but for qualitative spectroscopic information, no other detector scheme can acquire the amount of information that this simple two-dimensional detector can.