Preconcentration of trace of copper (II) ions using Bis (3-nitrobenzylidene)-1,2-ethanediimine(BCBEN) on multiwalled carbon nanotubes and subsequent determination by AAS

The determination of metal ions at trace level is very important in the content of environmental protection, food and agricultural chemistry as well as high purity materials. However, the direct determination of metal ions in complex matrices is limited due to their usually low concentrations and matrix interferences. In trace analysis, therefore, a preconcentration and/ or separation is necessary to improve sensitivity and selectivity of determination. Several procedures have been proposed and applied for enrichment and separation with atomic spectrometry detection according to the nature of the samples, the content of analytes and the measurement techniques [1–4]. Among them, the methods which are based on sorbent extraction have proven to be the most attractive ones due to their specificity and high preconcentration efficiency. The broad range of choice for sorbent materials along with various chelating reagents and eluents make this technique very attractive for sample pretreatment [5–9]. In the current study, a new sensitive and simple method for separation and peconcentration of Cu2+ ions from various real samples prior to its measurements by flame atomic absorption spectrometry (FAAS) is based on utilization of multiwalled carbon nanotube modifed with bis(3-nitrobenzylidene)-1,2-ethanediimine(BCBEN) as a solid phase extractant has been proposed. The influence of effective parametrs including pH, amount of ligand and solid phase, sample and eluent flow rate, and common coexisting ions on the Cu+2 ion recovery were examined. The optimum pH value for the separation and preconcentration of trace amount of Cu2+ ions on the new sorbent was 6.0, and its maximum static adsorption capacity onto the MWCNT- NBNBAEED was higher than 60.57 mgg−1 at this pH and a;er 1 h contact time. At optimum value of all variables, the response is linear over the range of 0.01-0.4 μg ml-1 and detection limit (3SDb/m, n=15) was 1.5 while respective preconcentration factor and enrichment factor was 200 and 36 and RSD was 3.1 %. The proposed procedure was applied to the analysis of various real samples.