Engineering of amino microporous organic network on zeolitic imidazolate framework-67 derived nitrogen-doped carbon for efficient magnetic extraction of plant growth regulators.

Development of efficient adsorbents for the enrichment of trace contaminants from complex matrix still remains great challenge and interest. Here we report the decoration of amino microporous organic network on zeolitic imidazolate framework (ZIF)-67 derived nitrogen-doped carbon (Co@NC-MON-2NH2) for efficient magnetic solid phase extraction (MSPE) of plant growth regulators (PGRs) from vegetables. The ZIF-67 was calcined to produce Co and N co-doped porous carbon (Co@NC), serving as the magnetic separation module and the core for in-situ growth of MON-2NH2 shell. The Co@NC-MON-2NH2 owned large surface area, good magnetic property and stability, giving high affinity to PGRs via multiple extraction mechanisms such as hydrogen bonding, π-π and hydrophobic interactions. Under optimal conditions, the Co@NC-MON-2NH2 based MSPE-HPLC-UV method gave wide linear range, good precisions, large enrichment factors, less adsorbent consumption and low limit of detections for the studied PGRs. The proposed MSPE-HPLC-UV method was also successfully applied to monitor the trace PGRs in diverse vegetables. These results not only revealed the promise of Co@NC-MON-2NH2 in extraction and adsorption of environmental contaminants from complex matrix, but also provided a new way to fabricate magnetic functionalized MONs in environmental science.