Atomic Emission Spectrometer/Spectrograph for the Determination of Barium in Microamounts of Diatom Ash

The development and routine application of a method for the determination of trace levels of barium in microsamples (5-10 mg) of diatom ash is described. Acid-dissolved lithium metaborate fusion melts of ash samples are analyzed using a spectrometer/spectrograph equipped with a dc argon plasma jet excitation source and an echelle diffraction grating. Sample, standard, and blank solutions are buffered by lithium contributed by the flux, to a degree sufficient to reduce matrix effects to acceptable levels. Previous barium determinations by other analytical techniques, on seven interlaboratory reference materials, have been used to establish the accuracy of our results. The average relative standard deviation for the instrumental analyses was 0.07. Using recommended instrument settings, moreover, the lowest concentration of barium visible in synthetic standard solutions lies Just below 2 μg/L, which is equivalent to 2 μg/g In the ash.