We have explored the feasibility of the methodology given in Section 2 using preconcentration with SDS-A for the determination of understudy metal ions in different real matrices by standard
addition method. Reliability was checked by spiking experiments and evaluating accuracy by standard addition method. The results for this study are presented in Table 3 and in Table 4. The recovery of spiked samples is satisfactorily reasonable and was confirmed using addition method, which indicates the capability of the system in the determination of the Ni2+, Zn2+, Cu2+ and Cr3+ ions. A good agreement was obtained between the added and measured analyte amounts. The recovery values calculated for the added standards were always higher than 95%, thus confirming the accuracy of the procedure and its independence from the matrix effects