Detection and determination of Zn (II) and Copper (II) cations by an effective solid phase extraction method (SPE) coupled by flame atomic absorption spectroscopy (FAAS) using dissolvable (nitrile acetic acid-nickel)-layered double hydroxide

Zn (II) cation (Zn2+) and Copper (II) cation (Cu2+), the required micro nutrient elements for organisms, plays an essential role in many biological processes, including oxygen transport, Enzyme catalysis, DNA and RNA synthesis, as well as cellular metabolism [1-3]. In this work, a simple, rapid and efficient method has been developed for extraction, and preconcentration of copper and iron ions in water samples by solid phase extraction coupled with flame atomic absorption spectrometry (FAAS). The metallic ions in the aqueous were complexed with nitriloaceticacid-nickel-layered double hydroxide (NTA-Ni-LDH) [4]. NTA-Ni-LDH was successfully synthesized and characterized and then used as dis-solvable sorbent in dispersive solid-phase extraction to pre-concentrate and separate Cu2+ and Fe3+ from aqueous phase due to the larger formation constant with NTA compared to Ni2+. The individual and interactive effect of process variables (pH, salt effect, extraction time, extraction temperature and absorbent amount) on the simultaneous extraction of cations were studied. The results showed that, temperature, pH, absorbent amount and time have significant effect on the extraction efficiency of copper and iron simultaneously. The experimentally obtained data were analyzed by analysis of variance (ANOVA) and second-order polynomial models. The developed models were predictive and good with high coefficient of determination (R2) values (more than 0.95). An optimization study using Derringer’s desired function methodology [5] was performed and the optimal extraction conditions were found to be extraction temperature of 35◦C, time of 30 min, adsorbent dosage of 3 mg, 0% (w/v) salt effect and pH of 6.5.