On-site separation and enrichment of heavy metal ions in environmental waters with multichannel in-tip microextraction device based on chitosan cryogel

A porous adsorbent based on cross-linked chitosan cryogel (CLCC) was facilely prepared and employed as extraction phase of home-made three channel-based in-tip microextraction apparatus (TBMA) for on-site separation and enrichment of heavy metal ions (Cu2+, Cd2+ and Pb2+) in various aqueous samples. Due to the abundant amino groups, the fabricated CLCC exhibited high coordination capability towards studied metal ions, the enrichment factors were in the range of 100-176. At the same time, the CLCC displayed excellent permeability and stability. The adsorption flow rate could be reached as high as 2.0 mL min(-1), which helped to reduce the extraction duration. Under the most suitable preparation conditions of CLCC and extraction parameters, the developed CLCC/TBMA was applied to field extract Cd2+, Cu2+ and Pb2+ and followed by quantification with atomic absorption spectrometry. The linear ranges for Cu2+, Cd2+ and Pb2+ ions were 0.50-500 ng L-1, 0.50-1000 ng L-1 and 1.0-1000 ng L-1, respectively, and the limits of detection located in the range of 0.080-0.21 ng L-1. Recoveries with different fortified contents varied from 82.2% to 111% with good reproducibility (RSDs% below 9%). The reliability and practicality of the established approach was well tested and verified with conventional laboratory sample preparation method. Results reveal that the introduced method not only possesses some features such as s high enrichment capability, satisfying sensitivity, quickness and cost-effectiveness, but also avoids the troublesome storage and transportation of large amount of water samples, and the detected concentrations can reflect the real contents of investigated metal ions in waters.

Automated summary

A highly efficient method for on-site separation and enrichment of heavy metal ions using a porous adsorbent based on cross-linked chitosan cryogel was successfully developed. This method offers features such as high sensitivity, quickness, cost-effectiveness, and accurate reflection of metal ion contents in water samples.