Novel amino-functionalized magnetic metal-organic framework/layered double hydroxide adsorbent for microfluidic solid phase extraction: Application for vitamin D3

Vitamin D deficiency is highly prevalent worldwide, especially with limited sun exposure and sun avoidance. Thus, reliable monitoring of vitamin D levels in food and biological samples is vital for medicinal diagnosis. Herein, a potent method for the extraction and determination of vitamin D3 is presented using a microchip-based solid-phase extraction (SPE) device followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. A new magnetic adsorbent based on Fe3O4 magnetic nanoparticles (MNPs) modified ZnFe layered double hydroxide (LDH)/2-aminoterephthalic acid-Zn2+ metal-organic framework (IRMOF-3) composite (IRMOF-3@MLDH) was successfully synthesized and fixed inside a rectangular micro-column (4 x 2 x 12 mm). The porous structure and high surface area of IRMOF-3@MLDH provide abundant adsorbing sites and make it a potent SPE adsorbent, with an exceptional ability to retain vitamin D3. The adsorption isotherm showed that the composite was highly efficient at extracting vitamin D3 with an extraction capacity of 126 mg g- 1. The designed extraction microchip simplified the SPE process, paving the way for automated SPE systems. The developed method presented a broad linear range of 5-2000 ng mL-1, with a detection limit of 1.4 ng mL-1. In comparison to conventional silica-based adsorbents, a higher sensitivity was obtained in the determination of vitamin D3 using the IRMOF-3@MLDH adsorbent. The selectivity of the method was also satisfactory, enabling the mea-surement of vitamin D3 in food and blood samples with high recovery values in the range from 95.2 to 101%. Thus, the newly developed adsorbent and method offer an efficient alternative to the commonly used C18-based approach.

Automated summary

This article introduces a new method for the extraction and determination of vitamin D3 using microchip-based solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. A new magnetic adsorbent (IRMOF-3@MLDH) based on Fe3O4 magnetic nanoparticles modified ZnFe layered double hydroxide (LDH)/2-aminoterephthalic acid-Zn2+ metal-organic framework was successfully synthesized and fixed inside a rectangular micro-column. The method showed a broad linear range, high sensitivity, and satisfactory selectivity and recovery values.