Micellar electrokinetic chromatography method for the simultaneous determination of furanic compounds in honey and vegetable oils

Recent Advancement in Fiber-Optic-Based SPR Biosensor for Food Adulteration Detection-A Review

Food safety is a scientific discipline that requires sophisticated handling, production, and storage. Food is common for microbial development; it acts as a source for growth and contamination. The traditional procedures for food analysis are time-consuming and labor-intensive, but optical sensors overcome these constraints. Biosensors have replaced rigorous lab procedures like chromatography and immunoassays with more precise and quick sensing. It offers quick, nondestructive, and cost-effective food adulteration detection. Over the last few decades, the significant spike in interest in developing surface plasmon resonance (SPR) sensors for the detection and monitoring of pesticides, pathogens, allergens, and other toxic chemicals in foods. This review focuses on fiber-optic SPR (FO-SPR) biosensors for detecting various adulterants in food matrix while also discussing the future perspective and the key challenges encountered by SPR based sensors.

Hydrogenation versus hydrogenolysis during alkaline electrochemical valorization of 5-hydroxymethylfurfural over oxide-derived Cu-bimetallics

The electrochemical conversion of 5-Hydroxymethylfurfural, especially its reduction, is an attractive green production pathway for carbonaceous e-chemicals. We demonstrate the reduction of 5-Hydroxymethylfurfural to 5-Methylfurfurylalcohol under strongly alkaline reaction environments over oxide-derived Cu bimetallic electrocatalysts. We investigate whether and how the surface catalysis of the MOx phases tune the catalytic selectivity of oxide-derived Cu with respect to the 2-electron hydrogenation to 2.5-Bishydroxymethylfuran and the (2 + 2)-electron hydrogenation/hydrogenolysis to 5-Methylfurfurylalcohol. We provide evidence for a kinetic competition between the evolution of H2 and the 2-electron hydrogenolysis of 2.5-Bishydroxymethylfuran to 5-Methylfurfurylalcohol and discuss its mechanistic implications. Finally, we demonstrate that the ability to conduct 5-Hydroxymethylfurfural reduction to 5-Methylfurfurylalcohol in alkaline conditions over oxide-derived Cu/MOx Cu foam electrodes enable an efficiently operating alkaline exchange membranes electrolyzer, in which the cathodic 5-Hydroxymethylfurfural valorization is coupled to either alkaline oxygen evolution anode or to oxidative 5-Hydroxymethylfurfural valorization.

In-pipette-tip kapok fiber-supported liquid extraction/in-situ derivatization coupled with high-performance liquid chromatography for conveniently determining three furfurals

This study presents an in-pipette-tip kapok fiber-supported liquid extraction/in-situ derivatization (in-pipette-tip KF-SLE-ISD) method for simultaneous enrichment and derivatization of furfurals. Briefly, 3 mg of natural kapok fiber, which was loaded in an assembled pipette-tip, was used to support 12.5 μL of extractant (ethyl acetate/toluene, 75:25, v/v) containing 10 mM 2,4-dinitrophenylhydrazine. The in-pipette-tip KF-SLE-ISD procedure was conveniently conducted by aspirating/releasing 1 mL of sample solution 10 cycles, allowing simultaneous extraction and derivatization of furfurals. Then, 100 μL of acetonitrile was aspirated/released 5 cycles for elution, 10 μL of which was directly analyzed by high-performance liquid chromatography. The limits of quantitation were in ranges of 0.10-0.45 μg/mL. The method showed satisfied linearity (R² > 0.99), precision (RSD < 8.53%) and relative recovery (90.34-114.71%), which was successfully applied to determine furfurals in various samples (e.g., honeys, juices and glucose injections). The proposed method has the merits of effectiveness, simplicity, low cost, wide availability and ease of automation.

One-pot derivatization/extraction coupled with liquid chromatography-tandem mass spectrometry for furfurals determination

Furfurals (5-hydroxymethylfurfural, furfural and 5-methyl furfural) have potential toxic effects to humans. This study developed a simple and rapid one-pot derivatization/extraction procedure for effective sample preparation of furfurals in complex samples prior to instrument analysis. The sample solution was incubated with 1-pyrenebutyric hydrazide (PBH) and hydroxyl-functionalized multi-walled carbon nanotubes (MWCNTs-OH) in a vial for 3 min. During this process, the furfurals were effectively derivatized by PBH and the furfural-PBH derivatives were selectively captured by MWCNTs-OH simultaneously. The detection selectivity and accuracy were greatly improved for the following liquid chromatography-tandem mass spectrometry analysis. Quantifying furfurals was validated over the 0.5-500 ng/mL concentration range with satisfactory linearities (R² >0.99), accuracies (84.7%-119.0%) and precisions (<9.0%). The limits of quantification of 0.30, 0.36 and 0.20 ng/mL for 5-hydroxymethylfurfural, furfural and 5-methyl furfural, respectively, were achieved. Finally, the validated method was successfully applied to determine furfurals concentrations in various samples.

Development of a bimetal-organic framework-polypyrrole composite as a novel fiber coating for direct immersion solid phase microextraction in situ supercritical fluid extraction coupled with gas chromatography for simultaneous determination of furfurals in dates

A new, simple, hyphenated technique couples supercritical fluid extraction and direct immersion SPME with GC-FID (SFE-DI-SPME-GC-FID) for the determination of 2-furaldehyde (2-F) and 5-hydroxymethylfurfural (5-HMF) in solid foods. A bimetal-organic framework-polypyrrole composite was grown in situ on stainless steel wire in solution and used as a novel solid phase microextraction (SPME) fiber coating. A central composite design based on a 2^n-1 fractional factorial experimental design was employed to optimize the SFE conditions for 2-F and 5-HMF at a pressure of 325 atm, temperature of 35 °C, dynamic extraction time of 15 min, and modifier volume of 150 μL. Also, the factors related to the solid-phase microextraction method including ionic strength, desorption time and temperature together with extraction time and temperature were optimized prior to the gas chromatography analysis. Under the optimal conditions, the limits of detection were in the range of 1.28-5.92 μg kg^-1. This method showed good linearity for 2-F and 5-HMF in the ranges of 40-50 000 and 4540-500 000 μg kg^-1, respectively, with coefficients of determination more than 0.9995. Single fiber repeatability and fiber-to-fiber reproducibility were less than 6.76% and 9.12%, respectively. The new method was successfully utilized to determine the amounts of 2-F and 5-HMF in the real solid food matrix without the need for tedious pretreatments.

SPR-Optical Fiber-Molecularly Imprinted Polymer Sensor for the Detection of Furfural in Wine

A surface plasmon resonance (SPR) platform, based on a D-shaped plastic optical fiber (POF), combined with a biomimetic receptor, i.e., a molecularly imprinted polymer (MIP), is proposed to detect furfural (2-furaldheide, 2-FAL) in fermented beverages like wine. MIPs have been demonstrated to be a very convenient biomimetic receptor in the proposed sensing device, being easy and rapid to develop, suitable for on-site determinations at low concentrations, and cheap. Moreover, the MIP film thickness can be changed to modulate the sensing parameters. The possibility of performing single drop measurements is a further favorable aspect for practical applications. For example, the use of an SPR-MIP sensor for the analysis of 2-FAL in a real life matrix such as wine is proposed, obtaining a low detection limit of 0.004 mg L⁻¹. The determination of 2-FAL in fermented beverages is becoming a crucial task, mainly for the effects of the furanic compounds on the flavor of food and their toxic and carcinogenic effect on human beings.

A New Enrichment Method for Quantification of 5-Hydroxymethylfurfural by Indirect Flame Atomic Absorption Spectrometry in Honey and Jam Samples

Background

Because of increasing amounts of 5-hydroxymethylfurfural (5-HMF) in processed foods and the complexity of the matrix, monitoring of trace 5-HMF requires accurate and reliable methods. Hence, an efficient sample pretreatment procedure is necessary for extraction and preconcentration of 5-HMF from the matrix.

Objective

In this study, a new and efficient sample preparation method utilizing ultrasound-assisted-cloud point extraction (UA-CPE), indirectly followed by flame atomic absorption spectrometry (FAAS), was introduced for the monitoring of trace amounts of 5-HMF in honey and jam samples.

Method

With this method, hydroxylamine was used as a derivatizing agent in the presence of Mn(II) and an anionic surfactant, SDS for extraction of 5-HMF at pH 9.0. For dispersing reagents in sample solution, low amounts of mixed surfactant, triton X-45 and SDS were mixed and fast-injected into the extraction media. A cloudy solution formed, and after reaction of 5-HMF with reagents, the cloudy solution was centrifuged. The extracted 5-HMF in the surfactant-rich phase was dissolved in acidic acetone and indirectly analyzed by FAAS.

Results

The method showed a detection limit of 1.27 μg/L in linear working range of 4–240 μg/L, good precision (2.3–6.5%), and recovery rates (93.5–97%) after preconcentration of 70-fold.

Conclusions

Within this study, an accurate and reliable method for the indirect quantification of 5-HMF in selected samples was successfully developed with a sensitivity improvement factor of 30.6.

Highlights

The figures of merit for the developed indirect method were appropriate. The applicability of the method for the analysis of 5-HMF in processed foods was excellent.