‘In-house’ validation for mobile nickel in solid environment samples

In the paper are presented the performance parameters for ‘in-house’ validation regarding the mobile Ni extracted from solid environmental samples polluted with high quantity of metallic elements using AAS technique. the extraction procedure was performed with two different extraction solutions: a mixture of 0.005 m EDTA, 0.1 m TEA and 0.01 m CaCl2, and another mixture with 1 m CH3COONH4 and 0.01 m EDTA. the experimental data for repeatability and intermediate precision obtained for both extraction methods applied to a polluted sewage sludge collected from an industrial wastewater treatment plant were situated under the RSD% limit value according to Horwitz and AOAC PVM. the recovery percentages were obtained on three different levels of concentrations and the mean of these values was situated in the accepted range. In the ruggedness tests were performed 8 experiments using full-factorial design for three factors. the factors selected for the extraction procedure were: time of extraction, report solid/solution and the rotative rate of the shaker. An uncertainty budget was developed and the conclusion was that three important factors influence the uncertainty value: the concentration of the sample, all steps repeatability and recovery values.