Sequential reagents release from layered effervescent tablets for simplifying multi-step sample preparation and extraction of metal ions from environmental samples

Sample preparation typically involves multiple steps to create conditions for separating analytes from the sample matrix. These steps involve the preparation of reagents and materials, their addition into the sample, mixing by external energy input, and timing of each step. All these steps increase analysis time, reduce sample throughput, and require benchtop laboratory equipment and trained personnel. In this work, we report layered effervescent tablets to simplify multistep sample preparation. The tablets consist of layers that dissolve sequentially at a controlled rate, releasing stored, pre-quantified reagents at specific time intervals. As a proof-of-concept demonstration, we designed tablets for the extraction of copper ions, as model analyte, from aqueous solutions. The tablets autonomously perform a series of steps that involve adjustment of pH, dissolution and dispersion of a chelating agent, incubation, mixing and extraction of the metal chelates in a magnetic sorbent by the action of effervescence. The preliminary analytical application of the method to the determination of copper in environmental samples revealed analytical features, which are comparable to standard laboratory practices (recoveries > 80%, RSD < 8%). In this manner it is demonstrated that layered effervescent tablets can be a promising tool for simplifying multistep sample preparation by reducing reliance on human and technical resources and allowing extractions to be performed with minimal intervention and basic infrastructure.