Facile preparation of metal organic framework-based laboratory semi-automatic micro-extraction syringe packed column for analysis of parabens in vegetable oil samples

A simple and efficient integrated, laboratory-made, semi-automatic microextraction packed in a syringe (Semi-automated MEPS) was first assembled and validated for the extraction of parabens in vegetable oils. Several representative metal–organic frameworks were prepared and used as sorbents for the direct extraction of analytes from diluted vegetable oils in a sealed syringe. The sorbent and adsorbed analytes were collected by an organic filter after syringe injection. After extraction, a simple device was used for the elution of analytes, which could greatly simplify the operation and reduce the total pretreatment time for oil matrix. High performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was used to separate and quantify parabens. Key factors affecting the extraction efficiency were investigated, such as volume ratio of oil sample to n-hexane, ultrasound extraction time, type and amount of sorbent, as well as the type, volume, and flow rate of elution solution. Under optimal conditions, the proposed method achieved low limits of quantification (1.97–4.57 ng/mL, S/N = 10) and good linearity (r > 0.9959) for all analytes recovered from various real samples. Relative standard deviations were calculated for all herbicides at two concentrations levels and were below 14.0%.