For total content determination all samples were diluted with
water and analyzed by ICP MS (ELAN 6100 ICP; PE-SCIEX, Canada)
equipped with Meihard-type nebulizer and Scott-type spray chamber.
Measurements were performed applying the following experimental
parameters: sweep: 5; number of replicates: 5; dwell time:
0.1 s; ICP RF power: 1100 W; lens voltage: 12 V; nebulizer gas
flow: 0.95 L min−1; plasma gas flow: 13.3 L min−1; sample flow
rate to the nebulizer: 1.0 mL min−1 and monitored isotopes: 203Tl
and 205Tl. Quantitative analysis program was used to automatically
correct the intensities of interfering isobaric and molecular
ions. For quantitative determinations the calibration curve method
was applied. Calibration points for Tl were 0 (blank), 1.0 and
10.0 μg L−1. Samples were diluted to obtain analyte concentration
within the range of the calibration curve. Correlation coefficient of
each calibration curve was equal or above 0.9999. Standard solution
(1.0 μg L−1 Tl) was analyzed after every 5–10 samples to control
instrumental drift.