2 in 1 versus 1 plus 1-Outcomes of the transformation of adsorptive stripping method for the Ni²⁺ and Co²⁺ determination

Due to the similar chemical properties of Ni2+ and Co2+, several dozens of adsorptive stripping voltammetric (AdSV) methods have been developed for their simultaneous determination. The question was would there be some benefits if a stripping method made for simultaneous determination of Ni2+ and Co2+ will be optimized for the determination of only one of them (Ni2+). It was found that the optimized method has for an order of magnitude lower LOQ (1.89x10(-10) M), an order of magnitude lower influence of Co2+, and the applicability of one calibration line for four orders of magnitude of Ni2+ concentration. The influence of some common anions and cations has been examined. The developed method was successfully applied for nickel content determination in real samples. The suitability of the developed method for the determination of Co2+ from the same solution in the second run, upon optimizations of deposition potential and time, was also explored. The LOQ obtained for Co2+ (3.61x10(-11) M) is almost two orders of magnitude lower than LOQ of the method for simultaneous determination of both cations and, its LOD and LOQ are among few lowest obtained by AdSV methods for Co2+ determination. The developed method for Ni2+ and Co2+ determination from the same solution in two successive runs has significantly better analytical performances than the starting method for their simultaneous determination in one run.