Validation of analytical methods ensures reliability and accuracy of analytical data. Accredited laboratories in accordance with the international standard ISO/IEC 17025, that is the Serbian standard SRPS ISO/IEC 17025, must fulfill and document the selection, validation, or verification of the analytical method. In the validation and verification process, it is mandatory to assess: limit of detection (LoD), limit of quantification (LoQ), linearity and measurement uncertainty.

The subject of this paper is validation the analytical method of determining the content of heavy metals Al, As, Cd, Cu, Fe, Mn, Ni, Pb i Zn in water using the mass spectrometry with inductively coupled plasma. The validation parameters that were studied are: linearity, limit of detection (LoD), limit of quantification (LoQ), recovery and precision (RSD). For determined analytes, the values of validation parameters were: LoD (0.011-2.23) mg/L, LoQ (0.03 - 3.4) mg/L, recovery (above 96 %) and the RSD (0.9-3.1) %.

The Bi0.5As1.5Te2.98Se0.02 single crystal in 11 mm?80 mm size was grown using the Bridgman method. Energy dispersive spectrometry (EDS) analysis was used to determine the chemical composition of the studied samples, as well as for checking and confirming the homogeneity of the samples. Mobility, concentration of charge majority carriers and Hall coefficient of single crystal, were determined using a Hall Effec system based on the Van der Pauw method. Hall Effect was measured at room temperature with four ohmic contacts and at temperature of liquid nitrogen with silver contacts with an applied magnetic field strength of 0.37 T at different current intensities. The expected improvement in the mobility of obtained single crystal doped with this content of arsenic was not obtained.