2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P77 MuLTICOMPONENT
MICRODETERMINATION OF ARSENIC,
ANTIMONy, TELLuRIuM, SELENIuM
bESIDES OF ThALLIuM by ICP-MS IN
wATERS
KRISTýnA URBánKOVá, JIří MACHáT and LUMíR
SOMMER
Brno University of Technology, Chemistry and Technology of
Environmental Protection, Purkyňova 118, 612 00 Brno,
urbankova@fch.vutbr.cz
Introduction
The concentration of As and Tl in the environment is
controlled by strict guidelines. Since considerable affection
of the human organism is described for As and Tl 1,2 . Te is
more toxic than Se but little is known about its requirements.
Se is longely known for its ambivalency and particular essentiality
for the human and animal organism and its implication
in various enzymes on trace levels. Arsenic compounds are
an important dopant for the semiconductor silicon production
and a modifier of mechanical properties in lead and copper
alloys. Complicated hydrolytic equilibria can be present in
dilute aqueous solutions in dependence on pH 3 .In fact, these
equilibria in aqueous solutions have little influence on the
results of ICP-MS only. The multicomponent microdetermination
of inorganic As, Sb, Se, Te and Tl with ICP-MS is
remarkable selective and sensitive and has not been studied
in detail 4 .
Experimental
C h e m i c a l s
Standard solutions of Se, Te, As, Sb and Tl with
100 μg dm –3 were prepared by dilution from original solutions
containing 1.000 ± 0.002 g dm –3 metals which were
purchased from Analytica s.r.o., Prague.
A multicomponent standard containing
1.000 ± 0.002 g dm –3 Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn,
na, ni, Pb, Ti, Zn was also from Analytica s.r.o. Prague.
The tuning solutions for ICP-MS were 1 mg dm –3 of
Ce 3+ , Li, Y, and Tl + in 2% HnO 3 . In such solution must be
the ratio CeO + /Ce + ≤ 1.5 % and Ce 2+ /Ce + ≤ 3 % for bivalent
ions. The solution containing 1 mg dm –3 of Co 2+ in 1% HCl
was used for tuning with the Helium collision cell.
I n s t r u m e n t a t i o n
An ICP-MS spectrometer Agilent 7500ce Japan was
used with a plasma generator of 27.12 MHz and the power
output 1,500 W. The sample nebulized by a concentric silica
nebulizer MicroMist with a cooled Scott chamber entered
by an injector of 2.5 diameters into the plasma.
The flow of the carrier argon trough the nebulizer was
1 dm 3 min –1 and contained the make up argon 0.33 dm 3 min –1 .
A constant temperature 2 °C of the nebulising chamber was
maintained.
s495
Results
no polyatomic interferences were observed for selected
isotopes 75 As, 82 Se, 121 Sb, 125 Te and 205 Tl such as Ar 2+ , ArH + ,
ArO + and Arn + . Six-points calibration plots for selected element
isotopes were strictly linear for concentrations less than
1,000 μg dm –3 in solutions containing 0.5% HnO 3 . The signal
intensity considerably decreases with the increasing concentration
of acids. For the hydrochloric acid the decrease is
6 % for 205 Tl and 11% for 75 As with 5% HCl, With HnO 3 ,
the decrease is 30% for 82 Se and 125 Te but for 75 As and 205 Tl
15%. The medium of 0.5% HnO 3 is optimal and recommended
for the measurement.
I n t e r f e r e n c e s
The effect of 1–250 mg dm –3 of na, K, Ca, Mg, Al,
Fe(III), on the signal intensity was evaluated for 100 μg dm –3
in 0.5 % HnO 3 . For 1–10 mg dm –3 of the matrix element the
error for the microelement signal does not exceed 5 %. For
50 mg dm –3 of the matrix element, the error for the microelements
increased to 15–20 % in the presence to Ca, Mg,
Al and Fe(III). On the other hand, 250 mg dm –3 of na and K
cause less than 10% error for 100 μg dm –3 As, Se, Sb, Te, Tl.
In the presence of 1–100 μg dm –3 of multicomponent
solution containing Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn,
na, ni, Pb, Ti, Zn with 100 μg dm –3 of 75 As, 82 Se, 121 Sb, 125 Te
and 205 Tl a considerable interference was observed and the
signal decreased up to 70 %. The error can be decreased in
the presence of 100 μg dm –3 of internal standard. 72 Ge was
suitable for 75 As in the He mode and 82 Se in the normal mode
and 209 Bi was suitable for the remaining elements measured
in normal mode (Fig. 1.).
A p p l i c a t i o n o f W a t e r S a m p l e s
Five-point strictly linear calibration plots with spiked
microelements were carried out for all kinds of waters. The
slopes of the regression lines were compared with that of ultra
pure water to evaluate the influence of the matrix which cause
some signal decrease by 5 %. This error can be diminished by
using internal standards especially for sea and mine waters.
Fig. 1. The influence of multicomponent standard on the intensity
of signal of 100 μg dm –3 of 75 As, 82 Se, 121 Sb, 125 Te and 205 Tl in
the presence or absence of internal standard ( 72 Ge and 209 bi)