An MOF-based dispersive micro solid phase extraction prior to dispersive liquid-liquid microextraction for analyzing plasticizers

In this study, for the first time, MOF-70 was applied as an adsorbent to develop an efficient and economical sample preparation method called dispersive micro solid phase extraction followed by dispersive liquid-liquid microextraction for the extraction and preconcentration of the migrated di-iso-butyl phthalate, di-n-butyl phthalate, di (2-ethylhexyl) adipate, and di-iso-octyl phthalate from the plastic containers into mineral water, injection serum, sterile distilled water, and carbonated soft drink. The adsorbent was synthesized and authenticated by X-ray diffraction, Fourier transform infrared spectrophotometry, scanning electron microscopy, and energy dispersive X-ray analysis. Initially, the target compounds adsorbed on the MOF particles by vortexing from a solution having dissolved Na2SO4. Then the mixture was centrifuged and the adsorbent particles were separated from the aqueous medium. 2-Propanol was utilized to elute the analytes from the adsorbent. Then, the eluate was mixed with carbon tetrachloride at mu L-level and hastily injected into an aqueous solution of Na2SO4. The obtained cloudy solution was centrifuged and an adequate of the sedimented phase was injected into the gas chromatograph equipped with a flame ionization detector. Satisfactory extraction recoveries (40-68 %), high enrichment factors (200-340), low limits of detection (0.88-1.04 mu g L-1) and quantification (2.90-3.43 mu g L-1), and wide linear ranges with the coefficients of determination >= 0.994 were obtained from the performed method. So little consumption of the MOF, elution solvent, and extractant is another advantage of the present research. Finally, the method is applicable for detection and determination of the studied plasticizers migrated into different drinks and liquids stored in plastic bottles to perform quality control analysis of the products.

Automated summary

For the first time, MOF-70 was used as an adsorbent to develop a sample preparation method for the extraction of harmful compounds from plastic containers into beverages, resulting in high extraction recoveries, enrichment factors, and low limits of detection.