Investigation of the use of charge-injection-device detectors for multielement atomic absorption spectrometry

Abstract

Graphite furnace atomic absorption spectrometry has excellent detection limits and accepts a wide variety of samples with little or no sample preparation. The method does, however, suffer from matrix interferences and a lack of highly capable multielement instrumentation. Continuum sources have been employed to GFAAS for multielement determinations, but the one dimensional array detectors used in these instruments can only observe a limited spectral range, limiting the multielement capabilities of these instruments. A continuum source, multielement graphite furnace atomic absorption spectrometer was developed here which employed a prototype echelle polychromator with charge injection device(CID) detection. The detection system employed a new device, the CID∼38, and camera control unit, the SCM5000E, with previously unavailable abilities. The camera system was developed and evaluated to determine its spectroscopic characteristics, and reprogrammed to provide rapid, continuous monitoring of many absorption signals simultaneously. A data acquisition and analysis scheme was developed for the prototype system, and the instrument demonstrated detection limits comparable to single-element line source GFAAS. The low ultraviolet throughput of the prototype echelle limited the spectral range that could be observed. Light scattering inside the spectrometer caused the sensitivity to decrease as the number of elements observed increased. A second echelle spectrometer system with higher wavelength resolution and increased throughput in the far ultraviolet was incorporated in to the instrument. The new system increased the spectral range which could be monitored, allowing more elements farther in the ultraviolet to be determined. The detection limits for the new system are comparable to single-element GFAAS, but degrade farther in the ultraviolet due largely to decreasing source output.