Efficient and straightforward spectrophotometric analysis of 5-hydroxymethylfurfural (HMF) using citrate@Fe3O4 nanoparticles as an adsorbent.

In this study, we developed a spectrophotometry method for the analysis of 5-hydroxymethylfurfuraldehyde (HMF) in pharmaceutical formulations using citrate@Fe3O4 adsorbent. As bare magnetite (Fe3O4) has certain limitations, such as aggregation and oxidation, surface modifications are commonly used to improve its properties. We successfully coated Fe3O4 with sodium citrate to create a magnetic adsorbent for isolating HMF from samples. We confirmed the successful surface coating of Fe3O4 with citrate using Fourier Transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Zeta potential, and scanning electron microscopy (SEM). The high adsorption capacity of citrate@Fe3O4 is due to the abundance of carboxyl and hydroxyl groups on the surface of the adsorbent, making it ideal for HMF extraction. The HMF concentration was then quantified using spectrophotometry. Citrate@Fe3O4 exhibited a high surface area and strong interaction with HMF. We analyzed the individual influential factors affecting the magnetic solid phase extraction (MSPE) setup. Validation parameters were also provided to confirm the reliability of the method. Under optimal parameters, the method exhibited excellent linearity in the range of 0.05-30.00 µg/ml with the lower limit of quantification (LLOQ) of 0.05 µg/ml. Relative standard deviations (RSD) values for precision were better than 10% and the method's trueness were better than 10%. Recoveries were found to be in the range of 85% to 106%, indicating excellent accuracy and reliability. We used this method to identify and measure HMF in six different dextrose pharmaceutical dosage forms as intravenous injectable solutions and three honey samples.

Hydrogels as Novel and Efficient Materials in Sorbent-Based Sample Preparation Techniques.

Recently, the application of hydrogel materials in sample preparation techniques has increased dramatically. This review discusses application of hydrogels in the field of sample preparation and focuses on extraction techniques practiced with hydrogel materials as sorbent and coating materials, and discusses their synthesis route. After introducing hydrogels, their applications in a variety of solid phase extraction methods (as one of the types of sample preparation techniques) are described. These methods include solid-phase microextraction (SPME), micro solid-phase extraction (µ-SPE) and magnetic solid-phase extraction (MSPE), in which hydrogels are used as the main adsorbent for the extraction and pre-concentration of heavy metals, pesticides, herbicides, insecticides, drugs and pigments. Also, the mechanism of adsorption of the above analytes by different hydrogels and the advantages of using hydrogels in the solid-phase extraction techniques are discussed. In the following, applications of pH-sensitive hydrogels as stimuli-responsive polymers, are discussed in the sample preparation field. Finally, conclusions and future perspectives are covered in the last section that will be very helpful for future studies.

A turn-on/off fluorescent sensor based on nano-structured Mg-Al layered double hydroxide intercalated with salicylic acid for monitoring of ferric ion in human serum samples.

The present work aimed to provide a novel chemosensor for ferric ion detection in human serum samples using nano-structured Mg-Al layered double hydroxide intercalated with salicylic acid (Mg-Al LDH-SA) as a sensitive fluorescence probe. The Mg-Al LDH-SA nanomaterial was synthesized and characterized via Fourier transform infrared spectroscopy, X-ray diffraction analysis, field emission scanning electron microscopy, dynamic light scattering and energy dispersive spectroscopy. The synthesized nanomaterial was applied to determine ferric ions by measuring the fluorescence intensity of Mg-Al LDH-SA sol solution at λem = 404 nm with excitation at λex = 287 nm. In the presence of ferric ions, the fluorescence intensity decreases owing to the formation of a stable complex between ferric ions and salicylic acid. Several important parameters affecting the analytical signal were studied and optimized. Under optimum conditions, the calibration graph was linear in the concentration range of 0.07-100 µmol L-1 with a corresponding detection limit of 26 nmol L-1. The intra- and inter-day relative standard deviations (n = 6 and ferric ion concentration; 50 µmol L-1) were 3.4% and 4.5%, respectively. The method was successfully employed to assess ferric ion in several human serum samples with relative recovery values between 98.7 and 104.6% for the spiked samples.

Dispersive liquid-liquid microextraction based on solidification of floating organic droplet followed by spectrofluorimetry for determination of carvedilol in human plasma.

BACKGROUND: Simple, chip and rapid analytical methods are required in biomedical analysis laboratories to support therapeutic drug monitoring units in hospitals. The present work aimed to provide such a method for quantitative determination of carvedilol in plasma samples. RESULTS: A new, simple, precise and efficient method was developed for the determination of carvedilol in human plasma using a dispersive liquid-liquid microextraction based on solidification of floating organic droplet, followed by spectrofluorimetry method. Some important parameters such as types and volumes of extraction and disperser solvents, pH, salt effect and sample volume were optimized. Under the optimized experimental conditions, the method provided a linear range of 40 to 300 ng ml(-1), with a correlation coefficient of 0.996. The limit of detection, lower limit of quantification and upper limit of quantification were 18, 40 and 300 ng ml(-1), respectively. The found recovery was from 98.2 to 102.2%, the mean intra- and inter-day precisions were 8.3 and 6.4%, respectively. The relative error for accuracy varied from 0.4 to 2.2%. The short-term temperature and freeze-thaw stability studies showed that carvedilol in human plasma was stable for sample preparation and analysis after storage. CONCLUSION: The proposed method provided reasonable acceptable results and could be used for therapeutic monitoring of carvedilol.