Abstract
The effects of calcium emission on the precision of flame atomic absorption spectrometric measurements of calcium in a nitrous oxide-acetylene flame are compared by using instruments that employ continuum or line radiation sources. The measurement precision obtained by using a wavelength-modulated echelle spectrometer with a Cermax xenon arc continuum source (WM-AAC) is found to be superior to that obtained with an instrument using a hollow cathode lamp line source when the calcium concentration exceeds 5 mg/L. The limiting noise at high calcium concentrations is analyte absorption flicker using WM-AAC and is analyte flame emission photon noise using the line-source instrument. No measurement biases are observed with either method for the analysis of an argillaceous limestone reference material, but measurement precision is better using WM-AAC at shorter integration times.
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