Simultaneous in situ derivatization and ultrasound-assisted dispersive magnetic solid phase extraction for thiamine determination by spectrofluorimetry

Investigating fluorogenic labelling of amine coupled with first-order derivative spectrofluorimetry as a versatile analytical methodology: Application to estimation of benoxinate in its eye drops

In this research, fluorogenic labelling followed by applying first-order derivative spectrofluorimetry for the developed fluorophore is discussed as an alternative, sensitive and selective analytical approach. Benoxinate, containing a primary amine and fluorescamine reagent were selected for the study. Then the proposed methodology relies on the reaction between the primary amine in benoxinate with fluorescamine that selectively reacts with primary amines to develop highly fluorescent products. The fluorescamine-benoxinate developed fluorophore is identified by its sharp first-order derivative peak at 465 nm following excitation at 386 nm in borate buffer, pH 8. The optimum reaction conditions were ascertained. Following ICH validation guidelines, the first order derivative of the relative fluorescence intensity for the developed fluorophore was linearly related to benoxinate concentration and ranged from 20.0 to 200.0 ng/mL with a detection limit of 3.36 ng/mL and a quantitation limit of 10.19 ng/mL, moreover, satisfying accuracy and precision values were obtained upon statistical analysis of results. The offered analytical method was successfully applied to quantify benoxinate in raw material and Benox® eye drops as a direct application to a commercial formulation.

Fluorescent characteristics of bee honey constituents: A brief review

The eligible articles were obtained from databases such as ScienceDirect, SciELO, PubMed and Springer. The searches were performed using the terms "honey", "vitamins", "fluorescence" and their combinations. The titles and abstracts of the articles found were read and revised to verify their relevance to the review. From the selected titles, it was possible to elaborate the systematic review, based on scientific studies and sources considered faithful and true. The systematic review presented confirms the necessity for studies to identify compounds using fluorescence techniques, using cheaper and more accessible techniques. Few studies are covered in this theme, when treated about Apis mellifera honey, and it has been observed that in the last 12 years, the few researches have only tried to show the viability of using the technique without quantifying the present compounds, while others demonstrate the fluorescent aspects, but performing through techniques considered more expensive.

Recent trends in analytical methods for water-soluble vitamins

In this review, recent advances in the analysis of water-soluble vitamins (WSVs) have been reported considering the advantages and disadvantages of various extraction, separation and detection techniques, commonly used for their quantification. Acid hydrolysis, enzyme treatment, SPE based methods and some other extraction methods have been discussed. Particular attention has been devoted to the analytical techniques based on liquid chromatography and electrophoresis. Furthermore, suitability and selectivity of hydrophilic interaction liquid chromatography (HILIC) for WSVs has been discussed in detail. Problems related to these techniques and their possible solutions have also been considered. Special focus has been given to the applications of liquid chromatography (since 2014-2019) for the simultaneous analysis of WSVs and their homologous in complex food samples.

Construction of a novel turn-on-off fluorescence sensor used for highly selective detection of thiamine via its quenching effect on o-phen-Zn2+ complex

In this work, a simple and selective fluorescence sensor approach called 'turn-on-off' for the determination of thiamine (TM) has been developed. As known, the o-phenanthroline (o-phen) has inner fluorescence, though when reacted with zinc ions to form the o-phen-Zn²⁺ complex the fluorescence intensity was enhanced effectively, while upon addition of TM into the o-phen-Zn²⁺ complex solution, the intensity of the system was gently quenched, which was termed the 'turn-on-off' probe. Notably, the method possessed highly selective, sensitive determination for TM with a detection limit of 0.25 μmol L^-1 and the reduced fluorescence intensity was proportional to the concentration of TM in the range 0.84-80.0 μmol L^-1 . Besides, the proposed mechanism was also investigated through exploring the Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy. Furthermore, this manner was successfully applied into practical samples for TM detection with satisfactory results.

A ferrocene/imprinted polymer nanomaterial-modified carbon paste electrode as a new generation of gate effect-based voltammetric sensor

Herein, a carbon paste electrode, concurrently incorporated with ferrocene and a molecularly imprinted polymer nanomaterial (Fc-MIP-CP electrode), is introduced as an innovative sensing platform for the detection of thiamine.

Novel synthesis of nanocomposite for the extraction of Sildenafil Citrate (Viagra) from water and urine samples: Process screening and optimization

A sensitive analytical method is investigated to concentrate and determine trace level of Sildenafil Citrate (SLC) present in water and urine samples. The method is based on a sample treatment using dispersive solid-phase micro-extraction (DSPME) with laboratory-made Mn@ CuS/ZnS nanocomposite loaded on activated carbon (Mn@ CuS/ZnS-NCs-AC) as a sorbent for the target analyte. The efficiency was enhanced by ultrasound-assisted (UA) with dispersive nanocomposite solid-phase micro-extraction (UA-DNSPME). Four significant variables affecting SLC recovery like; pH, eluent volume, sonication time and adsorbent mass were selected by the Plackett-Burman design (PBD) experiments. These selected factors were optimized by the central composite design (CCD) to maximize extraction of SLC. The results exhibited that the optimum conditions for maximizing extraction of SLC were 6.0 pH, 300μL eluent (acetonitrile) volume, 10mg of adsorbent and 6min sonication time. Under optimized conditions, virtuous linearity of SLC was ranged from 30 to 4000ngmL^-1 with R² of 0.99. The limit of detection (LOD) was 2.50ngmL^-1 and the recoveries at two spiked levels were ranged from 97.37 to 103.21% with the relative standard deviation (RSD) less than 4.50% (n=15). The enhancement factor (EF) was 81.91. The results show that the combination UAE with DNSPME is a suitable method for the determination of SLC in water and urine samples.

Magnetic Nanoparticles: From Design and Synthesis to Real World Applications

The increasing number of scientific publications focusing on magnetic materials indicates growing interest in the broader scientific community. Substantial progress was made in the synthesis of magnetic materials of desired size, morphology, chemical composition, and surface chemistry. Physical and chemical stability of magnetic materials is acquired by the coating. Moreover, surface layers of polymers, silica, biomolecules, etc. can be designed to obtain affinity to target molecules. The combination of the ability to respond to the external magnetic field and the rich possibilities of coatings makes magnetic materials universal tool for magnetic separations of small molecules, biomolecules and cells. In the biomedical field, magnetic particles and magnetic composites are utilized as the drug carriers, as contrast agents for magnetic resonance imaging (MRI), and in magnetic hyperthermia. However, the multifunctional magnetic particles enabling the diagnosis and therapy at the same time are emerging. The presented review article summarizes the findings regarding the design and synthesis of magnetic materials focused on biomedical applications. We highlight the utilization of magnetic materials in separation/preconcentration of various molecules and cells, and their use in diagnosis and therapy.

Determination of type A trichothecenes in coix seed by magnetic solid-phase extraction based on magnetic multi-walled carbon nanotubes coupled with ultra-high performance liquid chromatography-tandem mass spectrometry

Magnetic solid-phase extraction (m-SPE) is a promising sample preparation approach due to its convenience, speed, and simplicity. For the first time, a rapid and reliable m-SPE approach using magnetic multi-walled carbon nanotubes (m-MWCNTs) as the adsorbent was proposed for purification of type A trichothecenes including T-2 toxins (T2), HT-2 toxins (HT-2), diacetoxyscirpenol (DAS), and neosolaniol (NEO) in coix seed. The m-MWCNTs were synthesized by assembling the magnetic nanoparticles (Fe3O4) with MWCNTs by sonication through an aggregation wrap mechanism, and characterized by transmission electron microscope. Several key parameters affecting the performance of the procedure were extensively investigated including extraction solutions, desorption solvents, and m-MWCNT amounts. Under the optimal sample preparation conditions followed by analysis with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS), high sensitivity (limit of quantification in the range of 0.3-1.5 μg kg(-1)), good linearity (R (2) > 0.99), satisfactory recovery (73.6-90.6 %), and acceptable precision (≤2.5 %) were obtained. The analytical performance of the developed method has also been successfully evaluated in real coix seed samples. Graphical Abstract Flow chart of determination of type A trichothecenes in coix seed by magnetic solid-phase extraction coupled with ultra-high performance liquid chromatography-tandem mass spectrometry.