Enhanced Selectivity and Sensitivity for Flow Injection Spectrophotometric Determination of Cobalt Using Solid Phase Extraction with a 2D Ion-Imprinted Adsorbent

The present work reports the effectiveness of a 2D imprinting method based on a surface imprinting technique for the development of a selective and sensitive flow sorbent preconcentration system for Co²⁺ ion determination. Cobalt ions were determined by UV-vis spectrophotometry exploiting the complexation with 1-(2-piridylazo)-2-naphtol (PAN). Based on a coefficient of relative selectivity (k'), the ion-imprinted amino-functionalized silica gel sorbent (ISG), compared with modified but non-imprinted sorbent (MSG) and silica gel (SG), showed a very high selectivity. A limit of detection of 0.51 µg L^?1 and precision (n = 10) as a relative standard deviation of 2.63 and 1.50% for Co²⁺ concentration of 10.0 and 90.0 µg L^?1, respectively, were achieved. A comparison of the proposed method with other previously published methods shows advantages in terms of sample consumption, sample throughput, and limit of detection. The application of the present method was successfully performed for the direct determination of Co²⁺ content in urine and environmental water samples without any interference and without sample preparation, with satisfactory results.