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.