Determination of profenofos in seawater and foodstuff samples after its molecularly imprinted polymer pipette-tip micro solid phase extraction optimized by response surface methodology

Abstract

Background: In this research, a molecularly imprinted polymer (MIP) was synthesized and employed as a sorbent for pipette-tip micro solid phase extraction of profenofos insecticide in seawater, rice, and fish samples. The instrument employed for quantitation was spectrophotometry.

Results: Various factors affecting the microextraction protocol, including type and volume of the elution solvent, weight of MIP, pH and volume of sample solution, and number of cycles of loading and desorption were considered and optimized using one-factor-at-a-time, central composite design and Box-Behnken design. Factors optimized at: pH 4.0, amount of sorbent 2.5 mg, volume of methanol:acetic (9:1) acid as eluent 250 µL, both the number of extraction and elution cycles 5, and volume of sample 8.0 mL. At optimized conditions, an enrichment factor of 31 was achieved and the linearity range of the method was between 1.0 and 1000.0 µg/L. A good detection limit of 0.33 µg/L with a reproducibility better than 5.6% (as RSD) was observed.

Conclusion: The technique showed good analytical features for determination of profenofos in seawater, rice, and fish samples. Simplicity of operation of spectrophotometry and lack of using expensive HPLC grade solvents are other points of strengths of this method. The total analysis time was about 10 min, which is far less than techniques such as HPLC. Comparison between optimization with central composite design and Box-Behnken design showed better performance of the former.

Keywords: Food samples; Molecularly imprinted polymer; Pipette tip micro-solid phase extraction; Profenofos; Response surface methodology; Seawater analysis.

Fig. 1

Schematic representation of synthesize procedures of MIP utilizing PFF as target analyte. PFF and MAA were poured in of acetonitrile, then added of cross-linker EDMA, and AIBN (as starter) and then polymerization was performed. Imprinting process was completed with leaching the PFF of polymer

Fig. 2

Schematic procedure of proposed MIP- PT- µSPE. MIP was added in pipette- tip and sample loaded, then, the analytes were eluted and the eluent solution was transferred to a spectrophotometer for determination

Fig. 3

Absorbance spectra for 1000 µg/L of PFF without enrichment (a) and in optimum conditions after MIP extraction (b). The figure shown the analytical signal increased after MIP extraction

Fig. 4

Scanning electron microscope image of the prepared MIP (a) and NIP (b) sorbent that shows which the particles were densely and uniformly synthesized and their average size is about 200 nm

Fig. 5

FTIR spectra of MIP and NIP

Fig. 6

Behavior of MIP PT-µSPE and NIP PT-µSPE that proved higher sensitivity of MIP PT-µSPE