Aptamer Affinity Column Extraction Coupled With Immunochromatographic Strip for the Detection of Cadmium(II)

The presence of cadmium(II) (Cd(II)) in drinking water is a significant concern. While immunochromatographic strips often lack sensitivity for trace Cd(II) and are easily affected by coexisting ions. In this study, a specific Cd-aptamer affinity column (Cd-AAC) was developed for the extraction of Cd(II). The enriched Cd(II) was eluted using ethylenediaminetetraacetic acid and subsequently quantified rapidly with immunochromatographic strips. The preparation of the Cd-AAC, conditions of solid-phase extraction, the effects of interfering ions, and the reusability of the column were thoroughly investigated. Under optimal conditions, preconcentrating 10 mL of water samples achieved a limit of detection of 0.1 µg/L for Cd(II), with an enhancement factor of 10. The precision of the method (relative standard deviation, n = 6) was 3.1% and 1.6% for intra-batch, and 4.4% and 2.3% for inter-batch measurements of Cd(II) at 0.3 and 1.0 µg/L, respectively. The method was applied to the determination of Cd(II) in water samples, yielding results consistent with inductively coupled plasma mass spectrometry analysis. This approach is straightforward, rapid, economical, and sensitive.