A hydrochloric acid in-bottle digestion
procedure is used to partially digest wholewater
samples prior to determining
recoverable elements by various analytical
methods. The use of hydrochloric acid is
problematic for some methods of analysis
because of spectral interference. The inbottle
digestion procedure has been
modified to eliminate such interference by
using nitric acid instead of hydrochloric acid
in the digestion. Implications of this
modification are evaluated by comparing
results for a series of synthetic whole-water
samples. Results are also compared with
those obtained by using U.S. Environmental
Protection Agency (1994) (USEPA) Method
200.2 total-recoverable digestion procedure.
Percentage yields that use the nitric acid inbottle
digestion procedure are within 10
percent of the hydrochloric acid in-bottle
yields for 25 of the 26 elements determined
in two of the three synthetic whole-water
samples tested. Differences in percentage
yields for the third synthetic whole-water
sample were greater than 10 percent for 16
of the 26 elements determined. The USEPA
method was the most rigorous for
solubilizing elements from particulate matter
in all three synthetic whole-water samples.
Nevertheless, the variability in the
percentage yield by using the USEPA
digestion procedure was generally greater than
the in-bottle digestion procedure, presumably
because of the difficulty in controlling the
digestion conditions accurately.
