Application of molecularly imprinted polymer pipette tip micro-solid phase extraction of nalidixic acid and acetaminophen from pills and seawater samples and their determination by spectrophotometry

Application of a magnetically separable Zr-MOF for fast extraction of palladium before its spectrophotometric detection

In this research, a novel magnetic zirconium-based metal-organic framework (Fe3O4@SiO2@MIP-202, MMOF), was fabricated, fully characterized, and applied for the batch-mode solid phase extraction of trace amounts of Pd2+ ions from water and wastewater samples before its spectrophotometric detection. Pd2+ ions were desorbed from MMOF by nitric acid and were complexed by treating with KI solution to have a maximum absorbance at 410 nm. The synthesized MMOF composite showed a very large surface area (65 m2.g- 1), good magnetization (1.7 emu.g- 1) and a large pore volume (0.059 cm3.g- 1) with adsorption capacity of 194.5 mg of Pd2+ ions/g of the adsorbent. This nanosorbent boasts chemo-mechanical stability, high adsorption capacity due to its vast active sites, and facile recovery facilitated by its magnetic properties. Parameters affecting the extraction efficiency of the method were optimized as pH of the sample 7.4, volume of the sample 25 mL, 15 mg adsorbent, 1 mL of 0.1 M HNO3 eluent, with 10 and 15 min as the extraction and desorption times, respectively. The calibration curve was found to be linear across the 10.0-1500.0 µg.L- 1 range with a limit of detection of 1.05 µg.L- 1. The obtained extraction efficiency and enrichment were 98% and 245, respectively. The total analysis time was less than 30 min. This MMOF has never been used for the extraction of Pd2+ ions before.

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

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13065-022-00807-z.

Chromium-based metal organic framework for pipette tip micro-solid phase extraction: an effective approach for determination of methyl and propyl parabens in wastewater and shampoo samples

BACKGROUND

A chromium-based metal organic framework was synthesized and employed as an efficient sorbent for pipette tip micro-solid phase extraction and preconcentration of parabens from wastewater and shampoo samples up to sub-ppb level before their spectrophotometric analysis.

RESULTS

Factors affecting preconcentration including volume and type of solvent, amount of sorbent, number of extraction, and volume and pH of samples were optimized employing one-variable-at-a-time and response surface methodology. Obtained analytical characteristics of the method proves its usefulness for analysis of real samples. Linear range of the method for parabens was 1.0-200.0 μg/L. Detection limit of the protocol was 0.24 µg/L for propyl paraben and 0.25 µg/L for methyl paraben. Reproducibility of the protocol defined as % RSD was better than 5.78%. Synthesized adsorbent can be re-used for at least 20 extractions.

CONCLUSION

The method showed a good detection limit and precision for determination of methyl- and propyl-paraben in wastewater and shampoo samples.

Application of Molecularly Imprinted Polymers in the Analysis of Waters and Wastewaters

The increase of the global population and shortage of renewable water resources urges the development of possible remedies to improve the quality and reusability of waste and contaminated water supplies. Different water pollutants, such as heavy metals, dyes, pesticides, endocrine disrupting compounds (EDCs), and pharmaceuticals, are produced through continuous technical and industrial developments that are emerging with the increasing population. Molecularly imprinted polymers (MIPs) represent a class of synthetic receptors that can be produced from different types of polymerization reactions between a target template and functional monomer(s), having functional groups specifically interacting with the template; such interactions can be tailored according to the purpose of designing the polymer and based on the nature of the target compounds. The removal of the template using suitable knocking out agents renders a recognition cavity that can specifically rebind to the target template which is the main mechanism of the applicability of MIPs in electrochemical sensors and as solid phase extraction sorbents. MIPs have unique properties in terms of stability, selectivity, and resistance to acids and bases besides being of low cost and simple to prepare; thus, they are excellent materials to be used for water analysis. The current review represents the different applications of MIPs in the past five years for the detection of different classes of water and wastewater contaminants and possible approaches for future applications.

Vortex-Assisted Dispersive Molecularly Imprinted Polymer-Based Solid Phase Extraction of Acetaminophen from Water Samples Prior to HPLC-DAD Determination

In the present study, acetaminophen (ACT) molecularly imprinted polymer (ACT-MIP) were successfully synthesized via surface imprinting polymerization. The structural and morphological properties of ACT-MIP were characterized using various analytical techniques. ACT-MIP were used as an adsorbent in a vortex-assisted dispersive molecularly imprinted solid-phase micro-extraction (VA-d-μ-MISPE), coupled with a high-performance liquid chromatography–diode array detector (HPLC-DAD) method for the determination of ACT in water samples. Influential parameters such as the mass of adsorbent, vortex speed, extraction time, desorption volume, and desorption time were optimized using a multivariate approach. Under optimum conditions, the maximum binding capacities of ACT-MIP and NIP (non-imprinted polymers) were 191 mg/g and 71.5 mg/g, respectively. The linearity was attained across concentrations ranging from 0.630 to 500 µg/L, with a coefficient of determination of 0.9959. For ACT-MIP, the limit of detection (LOD) and limit of quantification (LOQ), enhancement factor, and precision of the method were 0.19 ng/L, 0.63 ng/L, 79, and <5%, respectively. The method was applied in the analysis of spiked water samples, and satisfactory percentage recoveries in the range of 95.3–99.8% were obtained.

The Use of Computational Methods for the Development of Molecularly Imprinted Polymers

Recent years have witnessed a dramatic increase in the use of theoretical and computational approaches in the study and development of molecular imprinting systems. These tools are being used to either improve understanding of the mechanisms underlying the function of molecular imprinting systems or for the design of new systems. Here, we present an overview of the literature describing the application of theoretical and computational techniques to the different stages of the molecular imprinting process (pre-polymerization mixture, polymerization process and ligand-molecularly imprinted polymer rebinding), along with an analysis of trends within and the current status of this aspect of the molecular imprinting field.