Attapulgite Nanoparticles-Modified Monolithic Column for Hydrophilic In-Tube Solid-Phase Microextraction of Cyromazine and Melamine.

In current study, a novel monolithic capillary column with embedded attapulgite nanoparticles has been developed and exploited as a stationary phase in hydrophilic in-tube solid phase microextraction (SPME) of cyromazine and melamine. The fibrillar attapulgite nanoparticles were embedded in the poly(1-vinyl-3-(butyl-4-sulfonate) imidazolium-co-acrylamide-co-N,N'-methylenebis(acrylamide)) (poly(VBSIm-AM-MBA)) monolith via in situ polymerization. The attapulgite/polymerization ratio of the monolith was finely optimized. Primary factors of in-tube SPME including sample solvent, elution solvent, sample loading volume, elution volume, sample loading flow rate, and elution flow rate were thoroughly evaluated. Under optimal conditions, the limits of detection (LODs) were found to be 21.1 and 0.3 ng mL(-1) for cyromazine and melamine in the milk formula sample, respectively. Also, the recoveries of cyromazine and melamine spiked in the sample ranged from 94.5% to 109.9% with RSDs less than 7.6%.