SORPTION OF ERYTHROSINE ONTO SILICA GEL MODIFIED BY CETYLPYRIDINIUM BROMIDE

In the current paper, adsorbent based on silica gel L 40/100 modified with cetylpyridinium bromide was obtained. The presence of cetylpyridinium cations on the silica gel surface was confirmed by the diffuse reflectance infrared fourier transform spectroscopy method. The sorption conditions of erythrosine from dilute aqueous solutions with the proposed sorbent were studied and optimized. It is shown that the use of modified silica gel allows efficient (>95%) extraction of erythrosine from aqueous solutions. Under optimal sorption conditions (pH 7, sorbent dosage 0.1 g and sorption time is 15 min), the sorption capacity of modified erythrosine sorbents was determined. It is shown that, with increasing temperature, a change in the isotherm type from the H‑type to the L‑type is observed. This change can be explained by the aggregation of erythrosin in solution, which is a competitive sorption process. It was shown that adsorption isotherms were well described by the Langmuir equation. Thermodynamic studies have made it possible to establish the spontaneous sorption. The desorption of erythrosine from the surface of silica gel modified with cetylpyridinium bromide was studied. It is shown that when using solutions of sulfuric acid, sodium hydroxide and distilled water, desorption does not occur. It was shown that the most effective eluent is solution of sodium dodecylsulfate in alkaline medium, and desorption of erythrosine occurs due to the destruction of ion pairs of dye anions with cetylpyridinium cations fixed on the surface. The data obtained can then be used to develop a test system for determination of erythrosine via corresponding colorimetric scales or for quantitative solid phase extraction and adsorption-spectroscopic quantification of erythrosine in some real samples.

β-Cyclodextrin Derivative Grafted on Silica Gel Represents a New Polymeric Sorbent for Extracting Nitisinone from Model Physiological Fluids

Nitisinone (NTBC) is used in the treatment of disorders affecting the tyrosine pathway, including hereditary tyrosinemia type I, alkaptonuria, and neuroblastoma. An inappropriate dosage of this therapeutic drug causes side effects; therefore, it is necessary to develop a rapid and sensitive method to monitor the content of NTBC in patients’ blood. This study aimed to develop anew polymeric sorbent containing β-cyclodextrin (β-CD) derivatives grafted on silica gel to effectively extract NTBC from model physiological fluids. The inclusion complex formed between β-CD and NTBC was examined by proton nuclear magnetic resonance spectroscopy. The novel sorbents with derivatives of β-CD were prepared on modified silica gel using styrene as a comonomer, ethylene glycol dimethacrylate as a crosslinking agent, and 2,2′-azo-bis-isobutyronitrile as a polymerization initiator. The obtained products were characterized via Fourier transform infrared spectroscopy and then used as sorbents as part of a solid phase extraction technique. High NTBC recovery (70%indicated that the developed polymeric sorbent may be suitable for extracting this compound from patients’ blood samples.

Development and Validation of QuEChERS Followed by UHPLC-ToF-MS Method for Determination of Multi-Mycotoxins in Pistachio Nuts

Pistachios are one of the types of tree nut fruits with the highest mycotoxin contamination, especially of aflatoxins, worldwide. This study developed a Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method that was followed by Ultra-High Performance Liquid Chromatography combined with Time-of-Flight Mass Spectrometry (UHPLC–ToF-MS) for the determination of mycotoxins in pistachios. Different approaches to dispersive solid phase extraction as a clean-up method for high lipid matrices were evaluated. For this, classic sorbents such as C18 (octadecyl-modified silica) and PSA (primary secondary amine), and new classes of sorbents, namely EMR-Lipid (enhanced matrix removal-lipid) and Z-Sep (modified silica gel with zirconium oxide), were used. The QuEChERS method, followed by Z-Sep d-SPE clean-up, provided the best analytical performance for aflatoxins (AFB1, AFB2, AFG1 and AFG2), ochratoxin A (OTA), zearalenone (ZEA), toxin T2 (T2) and toxin HT-2 (HT2) in pistachios. The method was validated in terms of linearity, sensitivity, repeatability, interday precision and recovery; it achieved good results according to criteria imposed by Commission Regulation (EC) no. 401/2006. The method was applied to real samples and the results show that pistachios that are available in Portuguese markets are safe from mycotoxins that are of concern to human health.

Synthesis and Characterization of Bagasse (Saccharumofficinarum L.) Silica Gel Modified Diphenylcarbazone

Bagasse is a solid waste from the sugar cane milling process in the sugar industry. The waste can be used as an ingredient in making silica gel which functions as an adsorbent. This can be done by changing its chemical structure composition to increase its role and function. This study aims to determine the characteristics of silica gel synthesized from bagasse (Saccharumofficinarum L.) and modified using diphenylcarbazone as much as 0.24 g with sol-gel technique. The characterization results obtained from Fourier transform infrared (FTIR) analysis of diphenylcarbazone modified silica gel, namely the absorption of Si-OH, Si-O-Si groups supported by the appearance of C꞊O, C꞊N, NH, and N꞊N groups. Characterization using x-ray diffraction (XRD) showed a change in amorphous silica to crystals, with the results obtained showing a crystal size of 41.468 nm.Abstrak: Ampas tebu merupakan limbah padat yang berasal dari proses penggilingan tebu pada produksi gula. Limbah tersebut dapat dimanfaatkan sebagai bahan pembuatan silika gel yang berfungsi sebagai adsorben. Hal tersebut dapat dilakukan dengan mengubah komposisi struktur kimianya agar dapat meningkatkan peran dan fungsinya. Penelitian ini bertujuan untuk mengetahui karakteristik silika gel yang disintesis dari ampas tebu (Saccharumofficinarum L.) dan dimodifikasi menggunakan difenilkarbazon sebanyak 0,24 gr dengan teknik sol-gel. Diperoleh hasil karakterisasi dari analisis fourier transform infrared (FTIR) terhadap silika gel termodifikasi difenilkarbazon menunjukkan adanya serapan gugus Si-OH, Si-O-Si yang didukung dengan pembentukan gugus C꞊O, C꞊N, N-H, dan N꞊N. Karakterisasi menggunakan difraksi sinar-x (XRD) menunjukkan perubahan silika amorf menjadi kristal dengan hasil yang diperoleh memperlihatkan ukuran kristal sebesar 41,468 nm.

Polyaniline modified silica gel coupled with green solvent as eco favourable mobile phase in thin layer chromatographic analysis of organic dyes

This article studies a new green eco-friendly TLC (thin layer chromatography) using silica gel and polyaniline modified silica gel as stationary phase in combination with ethyl acetate (EA), n-butyl acetate (BA) and butane-1-ol (BO) solutions as mobile phase for the comparative study of migration behaviour of organic dyes to identify the most suitable thin layer chromatographic system for the resolution of co-existing dyes. Better separation efficiency was observed by modifying silica gel with polyaniline as compared to pure silica stationary phase. Densitogrpahic presentation of separations achieved on polyaniline modified silica gel Pani@SG-EB1 was also presented. The thin layer chromatographic system comprising of polyaniline modified silica gel Pani@SG-EB1 as stationary phase and n-butyl acetate:DDW, 5:5 as green mobile phase was observed to be the most favourable for the separation of various combinations of three or four-component mixtures of organic dyes viz. methyl thymol blue, tartrazine, carmoisine, rose bengal, amidoblack 10B, bromopyrogallol red and 4-nitrobenzene dizonium tetrafluoroborate. The effect of presence of cations and anions on separation trend was also examined and the limits of detection of the separated organic dyes were estimated. Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron micrograph (TEM) studies were undertaken to characterize silica gel and modified silica gel (stationary phase). The developed method has been successfully applied for the identification of carmoisine in Solvin cold DS syrup and tartrazine in MefastTM syrup.

Adsorptive Removal of Anionic Azo Dye New Coccine Using Silica and Silica-gel with Surface Modification by Polycation

In the present work, adsorption of anionic azo dye, new coccine (NCC) on silica and silica-gel in an aquatic environment was discovered. Effective conditions such as adsorption time, pH, the influence of dosage on NCC adsorption using strong polycation, poly-diallyl-dimethylammonium chloride (PDADMAC) modified silica (PMS) and PDADMAC modified silica-gel (PMSG) were systematically studied. The removal of NCC using PMS and PMSG were much higher than that using raw silica and silica-gel without PDADMAC in all pH ranges from 3 to 10. The adsorption of NCC onto PMS and PMSG was achieved maxima at the same conditions of contact time 30 min, pH 6. The optimum adsorbent dosages of PMS and PMSG for NCC removal were 10 and 20 mg·mL−1, respectively. Experimental results of NCC adsorption isotherms onto PMS and PMSG at different ionic strength were fitted by Langmuir and Freundlich models. The NCC removal efficiencies using PMS and PMSG were higher than 87%, indicating that PMS and PMSG are novel and reusable adsorbents for removal of anionic dye. Based on adsorption isotherms, and surface group changes after PDADMAC modification and NCC adsorption examined by Fourier transform infrared spectroscopy (FTIR), we demonstrate that electrostatic interaction between positively charged adsorbents’ surfaces and negative sulfonic groups of NCC are the main driving force for anionic azo dye adsorption onto PMS and PMGS adsorbents.