8 research outputs found
Comparison of dissolution methods for multi-element analysis of some plant materials used as bioindicator of sulphur and heavy metal deposition determined
Most analytical methods for trace element determination in plant material require
decomposition of the sample. Sample decomposition procedures play an important role
in ensuring that chemical analysis gives correct results. This is especially important
in the determination of trace elements in plant material for environmental studies
because, as a rule, plant material is not homogeneous and usually contains variable
matrices. In this paper microwave digestion procedures using HNO, HNO+HO,
HNO+HClO, HF mixtures and dry ashing + HF were investigated for the analysis
of Al, Ca, Cr, K, Mg, Mn, Zn, S, Pb, V, Cu, Cd, Co and Ni by ICP-AES or ICP-MS
from pine needle samples. Reference samples BCR CRM 100 (Spruce Needles), BCR CRM 101
(Beech Leaves) and HUMH2 (Organic surface soil) were used to test the dissolution
methods. The results showed that the sample digestion procedure is critical step
for obtaining accurate results. Losses of volatile metals were notable in many
cases when dry ashing was used
Particle size distribution and dissolution properties of metals in cyclone fly ash
The particles in the examined cyclone fly ash were all smaller than
0.25 mm. in diameter, and particles smaller than 0.075 mm. in diameter
accounted for 88.4 % of the ash weight. This result indicates that
cyclone fly ash consists of particles with a small diameter. The metals
in the cyclone fly ash were enriched in small particles. The highest
concentrations for zinc, copper, lead, cadmium and molybdenum in the
cyclone fly ash were found in the smallest particle size fraction (<
0.075 mm.) and for Barium, chromium, nickel, Vanadium and Cobalt in the
second to smallest particle size fraction (0.0750.125 mm.). From an
environmental and toxicological standpoint, the smallest particles are
of the greatest concern when ash is handed at landfill disposal sites
(transport and disposal especially in stormy weather conditions), and
some studies have reported risks to workers from prolonged exposure to
ash. The results of the comparison of various dissolution methods for
metals showed that the digestion procedures with nitric acid alone
(USEPA 3051) or with a mixture of nitric acid + hydrogen peroxide
(USEPA 3050B) slightly underestimated the metal concentrations in the
cyclone fly ash. Although the use of hydrofluoric acid is often
necessary for the determination of a number of elements associated with
siliceous minerals, its use can result in loss of trace elements during
dissolution