Abstract:
Microwave digestions of mercury in Standards Reference Material (SRM) coal samples
with nitric acid and hydrogen peroxide in quartz vessels were compared with Teflon® vessel
digestion by using flow injection cold vapor atomic absorption spectrometry. Teflon® vessels
gave poor reproducibiUty and tended to deliver high values, while the digestion results from
quartz vessel show good agreement with certificate values and better standard deviations.
Trace level elements (Ag, Ba, Cd, Cr, Co, Cu, Fe, Mg, Mn, Mo, Pb, Sn, Ti, V and Zn) in
used oil and residual oil samples were determined by inductively coupled plasma-optical
emission spectrometry. Different microwave digestion programs were developed for each sample
and most of the results are in good agreement with certified values. The disagreement with
values for Ag was due to the precipitation of Ag in sample; while Sn, V and Zn values had good
recoveries from the spike test, which suggests that these certified values might need to be
reconsidered.
Gold, silver, copper, cadmium, cobalt, nickel and zinc were determined by continuous
hydride generation inductively coupled plasma-optical emission spectrometry. The performance
of two sample introduction systems: MSIS™ and gas-liquid separator were compared. Under the
respective optimum conditions, MSIS^"^ showed better sensitivity and lower detection limits for
Ag, Cd, Cu, Co and similar values for Au, Ni and Zn to those for the gas-liquid separator.
