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A simple stability-indicating reversed-phase high-performance liquid chromatography method has been developed for determination of elobixibat in presence of its potential impurities and degradation products. The chromatographic separation was carried on a Thermo scientific Base Deactivated Silica BDS Hypersil-C18 (150 × 4.6 mm; 5 μm) column using a mobile phase of acetonitrile and phosphate buffer (25 mM, pH 2.5) in a ratio of (70:30, v/v). The experimental conditions were accurately investigated, and the method was validated according to ICH guidelines Q2 (R1). The drug was subjected to various stress conditions including acidic, basic, oxidative, and photolytic conditions. The method successfully separates the drug from the three reported impurities and different degradants. The method was also successfully applied for the determination of elobixibat in laboratory prepared tablets (5.0 mg). Analysis shows no interference from excipients and degradation products. The method was also applied for performing in vitro dissolution testing of elobixibat laboratory prepared tablets. Since elobixibat is recently introduced into the market, there are no previous stability studies and no reported analytical methods for its determination. Thus, this study presents a validated and selective method that can be effectively employed in routine quality control studies.

This work presented a novel racemic imprinting process employing the chiral properties of chitosan monomer. The preparation of racemic ketoprofen (RS-KTP) imprinted polymer (RS-MIP) was conducted using glutaraldehyde as a crosslinker. The nature of elution solvent affected the % desorption ratio suggesting a heterogenous nature of the formed binding sites. Good imprinting was indicated by an imprinting factor of 3.50 for S-KTP. The enantioselectivity of the RS-MIP was indicated by enantioselectivity coefficient of 2.31 and % enantiomeric excess (%ee) of 28.55%. A SPE cartridge packed with RS-MIP enabled resolution of RS-KTP using gradient elution solvent system. Scatchard plot revealed two binding sites types of different affinity towards S-KTP and density observed for the RS-MIP. The binding capacity of RS-MIP showed observed dependence on the % ee of S-KTP indicating its enantioselectivity. The success of using racemic template for the preparation of enantioselective MIP brings a new possibility to achieve enantioseparation of racemic mixtures having very expensive or unavailable pure enantiomers.

Background: Favipiravir is an antiviral drug that was recently approved for the management of COVID-19 infection. Aim: This work aimed to develop a new method, using sugaring-out induced homogeneous liquid–liquid microextraction followed by HPLC/UV for the determination of favipiravir in human plasma. Materials & methods: The optimum extraction conditions were attained using 500 μl of tetrahydrofuran as an extractant and 1400 mg of fructose as a phase-separating agent. Results: The developed method was validated according to the US FDA bioanalytical guidelines and was found linear in the range of 25-80,000 ng/ml with a correlation coefficient of 0.999. Conclusion: These results showed that the developed method was simple, easy, valid and adequately sensitive for determination of favipiravir in plasma for bioequivalence studies.

Google Trends has been extensively used in different sectors from finance to tourism, the economy, fashion, the fun industry, the oil trade, and healthcare. This scoping review aims to summarize the role of Google Trends as a monitoring and a predicting tool in the COVID-19 pandemic. Inclusion criteria for this scoping review were original English-language peer-reviewed research articles on the COVID-19 pandemic conducted in 2020 using Google Trends as a search tool. Articles that were in a language other than English, were only in abstract form, or did not discuss the role of Google Trends during the COVID-19 pandemic were excluded. According to these criteria, a total of 81 studies were included to cover the period of the first year after the emergence of the crisis. Google Trends can potentially help health authorities to plan and control pandemics earlier and to decrease the risk of infection among people.

A new, simple, rapid and highly sensitive high performance liquid chromatographic method was developed for the determination of tobramycin (TOB) in ophthalmic solutions. The developed method was based on derivatizing this non-chromophoric drug with 2-naphthalenesulfonyl chloride (NSCl), at 80 ºC for 40 min, and measuring the fluorescent product. Elution from the column was isocratic, using a mobile phase consisting of acetonitrile –1% phosphoric acid in water, (90:10, v/v), with a flow rate of 2 mL/min, at 40 ºC. Determination was developed using fluorescence detection at an excitation wavelength of 300 nm and an emission wavelength of 380 nm. The chromatographic separation was achieved on Knauer-Eurospher 100–5 C18 silica column (300 mm × 4 mm i.d, 5 μm). Different approaches were used to optimize the conditions of the method and to reach the maximum yield. The linear regression data for the calibration plot showed acceptable correlation coefficient (r2 = 0.9998) at the concentration ranges of 2.5–1000 ng/mL for TOB. The method was successfully validated according to the guidelines of the International Council on Harmonization, and was found suitable for pharmaceutical applications. The method was new, simple and precise for analysis of TOB and applicable for routine analysis in quality control laboratories.

Liquid-liquid extraction is a widely used technique of sample preparation in biomedical analysis. In spite of the high pre-concentration capacities of liquid-liquid extraction, it suffers from a number of limitations including time and effort consumption, large organic solvent utilization, and poor performance in highly polar analytes. Homogeneous liquid-liquid extraction is an alternative sample preparation technique that overcomes some drawbacks of conventional liquid-liquid extraction, and allows employing greener organic solvents in sample treatment. In homogeneous liquid-liquid extraction, a homogeneous phase is formed between the aqueous sample and the water-miscible extractant, followed by chemically or physically induced phase separation. To form the homogeneous phase, aqueous samples are mixed with water-miscible organic solvents, water-immiscible solvents/cosolvents, surfactants, or smart polymers. Then, phase separation is induced chemically (adding salt, sugar, or buffer) or physically (changing temperature or pH). This mode is rapid, sustainable, and cost-effective in comparison with other sample preparation techniques. Moreover, homogeneous liquid-liquid extraction is more suitable for the extraction of delicate macromolecules such as enzymes, hormones, and proteins and it is more compatible with liquid chromatography with tandem mass spectrometry, which is a vital technique in metabolomics and proteomics. In this review, the principle, types, applications, automation, and technical aspects of homogeneous liquid-liquid extraction are discussed.

The applications of surfactants in various fields are gaining more attention, which makes full characterization of surfactants of growing interest. It is fundamental to measure the critical micelle...

Surfactants or surface-active agents are interesting groups of compounds with characteristic structures, allowing them to decrease the surface tension. A surfactant consists of a hydrophilic head and a hydrophobic tail. Typically, surfactant molecules aggregate into micelles at the critical micelle concentration. In this work, the concept of tautomerism has been successfully used for the determination of the critical micelle concentration of cetyltrimethylammonium bromide using curcumin as a colored probe. The ratio between diketo and keto–enol tautomers of curcumin increases by increasing the concentration of cetyltrimethylammonium bromide above the critical micelle concentration. This ratio can be monitored by measuring the absorbance ratio at Aλ360/Aλ428nm. The critical micelle concentration of cetyltrimethylammonium bromide was obtained from the inflection in the curve and was found to be 0.76 mM which agrees with the reported value.

A simple, fast, and green one-step microwave pyrolysis approach was proposed for the synthesis of highly fluorescent nitrogen/sulfur-doped carbon dots (NS-CDs). The proposed NS-CDs were prepared in only one minute from citric acid and thiosemicarbazide. In the presence of Cu

Biomass and biowastes stand as sustainable and cost-effective environmentally benign alternative feedstock. Chitosan is a biocompatible, bioactive, and biodegradable biopolymer derived from chitin to achieve eight aspects out of the 12 green chemistry principles. Chitosan got significant attention in several fields including chemical analysis, in addition to chemical functionally, which enabled its use as adsorbent and its structural crosslinking using various crosslinkers. The physicochemical, technological, and optical properties of chitosan have been extensively exploited in analysis. Mainly, deacetylation degree and molecular weight are controlling its properties and hence controlling its functions. This review presents a structure, properties, and functions relationships of chitosan. It also aims to provide an overview of the different functions that chitosan can serve in each analytical technique such as supporting matrix, catalyst…etc. The contribution of chitosan in improving the ecological performance is discussed in each technique.

Miniaturization of liquid-liquid extraction is a growing field of sample preparation to reduce solvent consumption, protect the environment, and preserve operators' health. In this work, four different modes of liquid-liquid microextraction have been compared including dispersive liquid-liquid microextraction, binary and ternary salting-out, and sugaring-out induced liquid-liquid microextraction. The extraction efficiency was evaluated by the enrichment factors of 14 different drugs from three pharmacological classes. Compared with the other modes, sugaring-out induced liquid-liquid microextraction was found to be the most efficient and, thus, it was applied for sample preparation of the antivirals in human plasma. Method optimization was performed using response surface methodology for the sugar type and amount (in mg), the sample pH, the equilibration time (in min), and the extractant volume (in µL). The method was then validated and found linear in the concentration range of 0.10-10 µg/mL for daclatasvir, 0.05-10 µg/mL for velpatasvir, and 0.20-10 µg/mL for ledipasvir, with correlation coefficients in the range 0.996-0.999. These results shows that sugaring-out induced liquid-liquid microextraction could be a more efficient microextraction mode for preparation of biological samples. Compared with other types of microextraction, sugaring-out induced liquid-liquid microextraction is greener, simpler, and cost-effective, with less tendency to affect the sample pH.

The coronavirus pandemic could be the most threatening outbreak in the twenty-first century. According to the latest records of world health organization, more than 130 millions have been infected by COVID-19, with more than 2.9 million reported deaths. Yet, there is no magic cure for treatment of COVID-19. The concept of drug repurposing has been introduced as a fast, life-saving approach for drug discovery. Drug repurposing infers investigating already approved drugs for new indications, using the available information about pathophysiology of diseases and pharmacodynamics of drugs. In a recent work, more than 3000 FDA approved drugs were tested using virtual screening as potential antiviral agents for COVID-19. In this work, the top ranked five hits from the previous docking results together with drugs of similar chemical feature and/or mechanistic destinations were further tested using AutoDock Vina. The results showed that anti-HCV combinations could be potential therapeutic regimens for COVID-19 infections. Supplementary information The online version contains supplementary material available at 10.1007/s13337-021-00691-6.

Refereed/Peer-reviewed The effect of hydrophilic/lipophilic balance (HLB) of polyoxyethylene ethers of different chain lengths on the microporogenic properties of the Brij surfactants has been studied. The objective of this work is to help better understand the role of each porogen and to set criteria for selecting the proper non-ionic surfactant, based on the HLB value. Seven recipes of different porogen compositions were first prepared and the highest efficiency was achieved using decane/decanol/dodecanol mixture with Brij® 30. Then, four other Brij surfactants covering the entire HLB scale were tested, and the prepared monoliths were characterized by SEM, BET, FT-IR and chromatography. The results showed that increasing the HLB from 9.72 to 18.84 was accompanied by an increase in monolith density and surface areas. The optimum HLB range was found to be 10 to 15. Surfactants of lower HLB formed either nonporous or less efficient columns, while those of higher HLB formed non-permeable columns. Adjusting the HLB was possible by mixing surfactants of different HLB. The prepared monoliths could be used in the isocratic mode with a mobile phase consisting of a mixture of ACN and water (20:80, v/v) at a flow rate of 1.5 μL min−1 to separate five sulfa drugs. The separation results showed that the elution order of the compounds correlated with their lipophilicity, with sulfamerazine (logp = 0.52) being the first to elute, and sulfaquinoxoline (logp=1.70) being the most retained. The asymmetry factors of the separated compounds ranged between 1.18 and 1.25, and the resolution was found to be in the range 2.92−7.80. The prepared monoliths could be also successfully separate a mixture of four different nonsteroidal anti-inflammatory drugs and a mixture of four benzoic acid derivatives. This work assists in optimizing the surfactant-based porogenic mixture to meet the desired porosity, surface area, morphology and chromatographic separation requirements.

Hepatitis C is a viral infection that has been declared as a global health problem by the World Health Organization. Egypt has the highest prevalence of hepatitis C virus (HCV) which results in a high morbidity and mortality from chronic liver disease, cirrhosis, and even hepatocellular carcinoma. Cities have lower rates of infection than rural areas. Studies about the abnormally high prevalence of HCV in Egypt ascribed that to the governmental campaign to treat Schistosoma. However, these treatment campaigns have stopped more than 35 years ago, which means that some other modes of transmission must have been involved. The objective of this work is to study the main reasons of HCV prevalence in the Egyptian Delta valley. A questionnaire-based study was conducted by members of the HCV Fighters project. Responses were collected from 949 volunteers (451 HCV patients and 498 healthy volunteers as control). The data were analyzed using SPSS version 19.0. The two-sample proportion test was used for statistical comparison between groups. The most probable risk factors of HCV transmission in Egypt included regular visits to dental clinics (55.2%), previous surgical operations (54.4%), former blood transfusion (52%), intrafamilial HCV infection (45.9%) and history of bilharzial infection (44.3%). Increasing public awareness about modes of transmission and risk factors of HCV infection is a must, especially within family members of HCV patients. Strict commitment to proper medical care precautions by health care practitioners is required.

In this study, a novel and simple fluorescent carbon quantum dots (CQDs) based nano-sensor for colchicine determination has been prepared. The nitrogen doped CQDs probe was prepared using uric acid as a carbon/nitrogen source via a one-step pyrolysis. The sensor is based on inner filter effect (IFE) where colchicine acts as a powerful absorber that affects the excitation of the fluorescer (CQDs). This overlap results in a quantitative attenuation of the fluorescence of CQDs with increasing colchicine concentration in the range of 2–25 μM. The developed sensor has the advantages of simplicity, less time-consuming, convenience and satisfactory selectivity for colchicine determination in pharmaceutical dosage forms.

The possible renal and hepatic toxicities of ethylenediaminetetraacetic acid (EDTA) in bean cooking media were studied using 100 male albino mice. Two sublethal doses of EDTA were used to explore their toxic effects; 20 mg/kg and 200 mg/kg, which corresponded to 1/100th and 1/10th of LD50, respectively. Accordingly, the toxicity study was performed using 50 mice, divided into five groups ( n = 10/group) as follows: group 1 (Gp1) served as a negative control and was orally administered normal saline; group 2 (Gp2) was administered the bean cooking medium; group 3 (Gp3) was administered EDTA (200 mg/kg); group 4 (Gp4) was administered bean cooking medium containing 20 mg/kg of EDTA; and group 5 (Gp5) was administered bean cooking medium containing 200 mg/kg of EDTA. The results showed no significant changes in liver and kidney functions in Gp2 while Gp3, Gp4, and Gp5 exhibited significant increases in adverse liver and kidney function markers. Hematocrit values were significantly decreased in Gp3 and Gp5, while the total white blood cells counts were significantly decreased in Gp3 and significantly increased in Gp5. The number of platelets was decreased in Gp3, Gp4, and Gp5. The blood levels of sodium (Na+), iron (Fe2+), and calcium (Ca2+) were decreased in Gp3, Gp4, and Gp5 due to the chelating effects of EDTA. The hepatic and renal architectures were disorganized in Gp3, Gp4, and Gp5 with some hemorrhagic manifestations in livers and kidneys of mice. These results demonstrate that EDTA in bean cooking is harmful in mice under the conditions of this study, and the potentially harmful effects in humans supports restricting its use.

Favipiravir is a potential antiviral medication that has been recently licensed for Covid-19 treatment. In this work, a gadolinium-based magnetic ionic liquid was prepared and used as an extractant in dispersive liquid-liquid microextraction (DLLME) of favipiravir in human plasma. The high enriching ability of DLLME allowed the determination of favipiravir in real samples using HPLC/UV with sufficient sensitivity. The effects of several variables on extraction efficiency were investigated, including type of extractant, amount of extractant, type of disperser and disperser volume. The maximum enrichment was attained using 50 mg of the Gd-magnetic ionic liquid (MIL) and 150 μl of tetrahydrofuran. The Gd-based MIL could form a supramolecular assembly in the presence of tetrahydrofuran, which enhanced the extraction efficiency of favipiravir. The developed method was validated according to US Food and Drug Administration bioanalytical method validation guidelines. The coefficient of determination was 0.9999, for a linear concentration range of 25 to 1.0 × 10

The recently introduced gadolinium-based magnetic ionic liquid (Gd-MIL) has been exploited as an extractant in dispersive liquid–liquid microextraction (DLLME) for preconcentration of ivermectin (IVR) from water samples followed by analysis using reversed-phase HPLC with UV detection at 245 nm. The utilized Gd-MIL extractant is hydrophobic with markedly high magnetic susceptibility. These features result in an efficient extraction of the lipophilic analyte and facilitate the phase separation under the influence of a strong magnetic field, thus promoting the method sensitivity and increasing the potential for automation. To maximize the IVR enrichment by DLLME, the procedure was optimized for extractant mass, dispersive solvent type/volume, salt addition and diluent pH. At optimized conditions, an enrichment factor approaching 70 was obtained with 4.0-mL sample sizes. The method was validated in terms of accuracy, precision, specificity and limit of quantitation. The method was successfully applied to the determination of IVR in river water samples with a mean relative recovery of 97.3% at a spiked concentration of 400 ng/mL. Compared with other reported methods, this approach used a simpler procedure with improved precision, lower amounts of safer solvents and a short analysis time.

Ascorbic acid has recently been extensively used due to its role in the management of COVID-19 infections by stimulating the immune system and triggering phagocytosis of the corona virus. The currently used spectrofluorometric methods for determination of ascorbic acid require using derivatizing agents or fluorescent probes and suffer from a number of limitations, including slow reaction rates, low yield, limited sensitivity, long reaction times and high temperatures. In this work, we present a highly sensitive spectrofluorometric method for determination of ascorbic acid by switching-on the fluorescence of salicylate in presence of iron (III) due to a reduction of the cation to iron (II). The addition of ascorbic acid resulted in a corresponding enhancement in the fluorescence intensity of iron (III)-salicylate complex at emission wavelength = 411 nm. The method was found linear in the range of 1-8 µg/mL with a correlation coefficient of 0.9997. The limits of detection and quantitation were 0.035 µg/mL and 0.106 µg/mL, respectively. The developed method was applied for the determination of ascorbic acid in the commercially available dosage form; Ruta C60® tablets. The obtained results were compared with those obtained by a reported liquid chromatographic method at 95% confidence interval, no statistically significant differences were found between the developed and the reported methods. Yet, the developed spectrofluorometric method was found markedly greener than the reference method, based on the analytical Eco-scale and the green analytical procedure index. This work presents a simple, rapid and sensitive method that can possibly be applied for determination of ascorbic acid in pharmaceuticals, biological fluids and food samples.

Guaiacol (GUA) and pholcodine (PHO) were simultaneously determined in a pharmaceutical syrup using RP-HPLC with UV detection. The separation was performed using X-Bridge C8 column (100 mm × 4.6 mm, 2.5 μm particle size) and a mobile phase of acetonitrile – phosphate buffer (pH 6.8; 50 mM) (25:75, v/v) at a flow rate of 0.55 mL/min. The column temperature was adjusted to 35°C, and the detector was set to measure the absorbance at 238 nm. The ICH guidelines were followed to validate the method. The linearity was studied over 6.0 – 70 μg/mL and 4 – 420 μg/mL ranges for GUA and PHO, respectively. Linear relationships were obtained over the specified concentration ranges with correlation coefficients of 0.9989 for GUA and 0.9999 for PHO. The limits of detection were also determined and found to be 2 μg/mL for GUA and 1.2 μg/mL for PHO. The proposed method was applied for the determination of both drugs in Coughpent syrup; the results comply with the label claim (0.1572g/120mL for PHO and 0.0237g/120mL for GUA).

Porogens are key components required for the preparation of porous polymer monoliths for application in separation science. Porogens determine the stability, selectivity, and permeability of polymer monoliths. This review summarizes the role of porogens in the preparation of porous polymer monoliths with a focus on clear understanding of effect of porogens on morphological properties, porosity, surface area, mechanical stability, and permeability of monoliths, particularly targeting the field of separation science. This review also includes the use of different types of porogens with the focus on various approaches used to set criteria for their systematic selection, including porogen-free techniques recently used for synthesis of porous monoliths. It discusses the current state-of-the-art applications of porogens in column preparation as well as where the future developments in this field may be directed.

Ibandronate sodium monohydrate is a highly polar aliphatic compound that belongs to the bisphosphonate class, a widely used bone resorption inhibitor. The aliphatic nature of ibandronate precludes direct photometric detection and its high polarity urged analysts to use ion-pairing agents in the mobile phase to promote retention in reversed-phase columns. In this work, a reversed-phase method for determination of ibandronate sodium monohydrate in pharmaceutical tablets is introduced by employing an online postcolumn ligand exchange reaction to enable photometric detection. The method offers for the first time the ability to separate the drug from its well-known impurities on conventional reversed-phase columns. The detection reaction depends on the ability of ibandronate and its degradation products to displace salicylate in the iron(III) salicylate complex, forming various colorless iron (III) complexes and showing a negative chromatographic signal for ibandronate and its degradants at λmax = 525 nm. The chromatographic separation was achieved using a Hypersil BDS C8 column (5 µm particle size, 150 mm × 4.6 mm i.d.) and a mobile phase consisting of a mixture of aqueous formate buffer pH 3 (pH 3, 5 mM) and methanol in a ratio of 80:20% (v/v), delivered at a flow rate of 0.8 mL/min. The postcolumn iron(III) salicylate reagent was prepared at 250 µM in aqueous formate buffer, delivered using a syringe pump at a flow rate of 0.5 mL/min. The proposed method was validated as per the guidelines of the International Conference on Harmonization Q2(R1) and was found linear over the range 40–120 µg/mL (r = 0.9995) with a limit of detection of 3.19 µg/mL. Compared to currently reported methods, the proposed method is considerably simpler, faster, cheaper, and adequately sensitive and makes use of the most popular LC detectors.

Iron oxide nanoparticles (IONPs) gained a lot of interest in biomedical research and have been approved for clinical application for years. IONPs are tamed for use in several biomedical applications such as hyperthermia, drug delivery, magnetic resonance imaging and theranostics. Hence, they perform multiple tasks in the treatment, diagnosis and targeting of diseases like cancer. The unique physical and chemical properties of IONPs allowed conducting further modifications improving their biocompatibility, targeting ability and circulation retention time. These modifications include biocompatible polymer coating, ligand functionalization and more which are called surface decorations. This paper reviews the biomedical applications of IONPs, gives a brief idea about the most common preparation methods including; co-precipitation, sol-gel method, spray/laser pyrolysis and sonolysis, and spots their main drawbacks and how to reduce them via surface modifications. These surface modifications like coating performs various functions on molecular, physical and biological behavior of IONPs after in vivo administration. Surface coating not only improves the drug pharmacodynamics but also optimizes the pharmacokinetics of the body via escaping the rapid elimination “stealth effect” and increasing the retention time of the nano-system within the body. The other face of surface modifications is the ligand functionalization as a targeting tool which is discussed in detail at receptor-mediated endocytosis targeting method. This review covered possible methods of targeting IONPs to the specific site of action either by direct local injection, enhanced permeability and retention of the tumor or diseased tissue, external magnetic field guidance, or receptor-mediated endocytosis based on over-expressed receptors on target cell.

Three methods were developed for simultaneous determination of diclofenac and esomeprazole in their binary mixtures. Method I is dual wavelength spectrophotometry which is based on measurement of absorbance difference ΔA (281.7–315 nm) for determination of diclofenac and ∆A (262.6–301.6 nm) for determination of esomeprazole. Method II is derivative spectrophotometry which is based on measuring 1D at 301.6 nm for determination of diclofenac and 2D at 299.5 nm for determination of esomeprazole. Linearity ranges were found to be 5–25 and 2‒10 μg/mL for diclofenac and esomeprazole, respectively, using methods I and II. Method III is reversed phase HPLC method which involves separation of diclofenac and esomeprazole on XBridgeTMC18 column using a mobile phase consisting of ethanol-phosphate buffer solution (pH 4, 60 : 40, v/v). The flow rate was 1.5 mL/min with ultraviolet detection at 290 nm. The calibration graphs are linear from 2 to 120 μg/mL for diclofenac and from 5 to 60 μg/mL for esomeprazole.

Ibandronate is a non-chromophoric bisphosphonate drug containing a tertiary amine group, which does not easily react with chromophoric and chromogenic agents. The current report describes the devel...

Quantitative analysis of phenolic compounds in Aloe arborescens fermented extract revealed that barbaloin concentration was found to be 14 μg/mL (14 ppm) by HPLC analysis. Seven phenolic compounds could be identified: aloesin, 8-C-glycosyl-7-O-methyl-S-aloesol, aloenin, isobarbaloin, barbaloin, 2 -O-feruloylaloesin, and aloe-emodin based on previous HPLC analysis. Short chain fatty acids such as acetic, propionic, butyric, lactic acid, were identified in the fermented extract of A. arborescens by GC/MS analysis. Reduction of barbaloin concentration and production of butyric acid clearly indicate a potential efficacious role of endophytic bacteria in A. arborescens leaves. Dietary intake of the extract fermented by endophytic bacteria in A. arborescens highlights immune-stimulating activity to human health and strongly influences an importance of host-microbial crosstalk to ensure maintenance of homeostasis.

Fixed dose combinations of glutathione and ascorbic acid are marketed due to the synergetic effect of glutathione, which regenerates ascorbic acid, potentiates its action and prolongs its antioxidant potential. In this work, glycerol was introduced for the first time as a green mobile phase modifier for liquid chromatographic determination of glutathione and ascorbic acid in pharmaceutical tablets. The viscosity barrier was overcome by using water as a co-fluidifying solvents and by controlling the column temperature. Compared with methanol and acetonitrile, glycerol could result in better peak shapes and superior system suitability. To explore the retention process, free energy and enthalpy-entropy compensation were calculated for both glutathione and ascorbic acid. The chromatographic conditions were optimized using factorial design with the aid of Minitab 17® Software. The method was successfully validated according to the guidelines of the International Conference on Harmonization Q2 (R1) and was found linear in the range of 1 μg/mL to 300300 μg/mL for both drugs. The method was evaluated in terms of its greenness and then compared to the reported method. Glycerol has several advantages over commonly employed mobile phase modifiers, such as the high safety, the low UV cut-off point, low flammability, low volatility, the green features, and the biodegradability. This work paves the way for more applications of glycerol in green liquid chromatography.

In this study, a novel and simple fluorescent carbon quantum dots (CQDs) based nano-sensor for colchicine determination has been prepared. The nitrogen doped CQDs probe was prepared using uric acid as a carbon/nitrogen source via a one-step pyrolysis. The sensor is based on inner filter effect (IFE) where colchicine acts as a powerful absorber that affects the excitation of the fluorescer (CQDs). This overlap results in a quantitative attenuation of the fluorescence of CQDs with increasing colchicine concentration in the range of 2-25 μM. The developed sensor has the advantages of simplicity, less time-consuming, convenience and satisfactory selectivity for colchicine determination in pharmaceutical dosage forms.

The effect of adding ethoxylated sorbitan ester surfactants (Tweens®) to poly(ethylene glycol) diacrylate-based monolithic recipes was investigated. Five different Tweens® have been evaluated to investigate the exact role of non-ionic surfactants in poly(ethylene glycol) diacrylate-based monolith preparations. These monoliths were characterized by scanning electron microscopy, infrared spectroscopy, and nitrogen physisorption analysis. Different morphological features, and surface areas were observed when different types of Tween® were included in the recipe; Tween® 20 and 85 showed small globules, while Tween® 40, 60 and 80 exhibited larger globular structures with different sizes and degrees of coalescence. The different Tween®-based monoliths were investigated for the chromatographic separation of mixtures consisting of hydroxybenzoic acids and alkylbenzenes. These columns were mechanically stable, except for Tween® 80. The highest methylene selectivity and the best overall performance were achieved by Tween® 60. The efficiency was increased by increasing the concentration of the Tween® 60 and the amount of poly(ethylene glycol) diacrylate Mn 700 in the recipes up to 30 wt%, each. Further increases in either Tween® 60 or poly(ethylene glycol) diacrylate Mn 700 led to formation of non-permeable columns. The optimized column was successfully used for separation of mixtures of nonsteroidal anti-inflammatory and sulfa drugs, with a maximum efficiency of 60,000 plates/m. Refereed/Peer-reviewed

The influence of the addition of various non-ionic surfactants to poly(ethylene glycol) diacrylate-based monolith formulations was studied. Eight non-ionic surfactants having different chemistries were chosen for this study. These surfactants were Brij L4, Span 80, IGEPAL CO-520, Tergitol 15S9, 2, 4, 7, 9-tetramethyl-5-decyne-4, 7-diol ethoxylate, Tween 40, Triton X-405, and Tetronic 701. The chemical structures of these surfactants have a variety of functional groups and cover a wide range of molecular weights (360–3600 g/mol), viscosities (60–1500 cP), and hydrophilic–lipophilic balances (1.0–17.6). The formed polymers were characterized by scanning electron microscopy, surface area measurement by the Brunauer–Emmet–Teller method, elemental analysis, and Fourier transform infrared. Four formulations, involving the use of surfactants, resulted in permeable materials when prepared in 150 μm ID silica capillaries. The chromatographic performance of the resulting columns in reversed-phase mode was evaluated and compared using a mixture of alkyl benzenes as test analytes. The highest efficiency and methylene selectivity were observed when Tween 40 was included in the formulation, using decane/decanol/dodecanol as coporogens. This porogenic mixture was successfully used for preparation of monolithic columns from a selection of methacrylate- and styrene-based monomers, including butylmethacrylate, hydroxyethymethacrylate, laurylmethacrylate, glycidyl methacrylate, bisphenol diacrylate, benzylmethacrylate, and N,N-dimethylacrylamide, as well as for divinylbenzene. These results show the applicability of this porogenic mixture for a variety of monolithic formulations, providing an approach for developing a universal porogen system. Refereed/Peer-reviewed

Salting-out induced liquid-liquid microextraction method has been developed for plasma sample treatment before determination of alogliptin by high performance liquid chromatography with UV detection. Several parameters were optimized to achieve maximum enrichment, including type of extractant, volume of extractant, type of anion, type of cation, salt amount and pH. The optimum conditions were attained using 500 µL of acetonitrile, added to 1 mL of aqueous sample containing 250 mg of sodium chloride at pH 12. An RP-HPLC method was developed and validated according to the International Conference on Harmonization guidelines M10. The method was linear in the concentration range of 0.1 to 50 µg /mL (correlation coefficient= 0.997). The limit of detection was 0.019 µg/mL and limit of quantitation was 0.06 µ g/mL. The method was accurate and precise with an average % recovery of 99.7% and a % relative standard deviation ranging between 1.5 and 2.5. These results showed that the salting-out induced liquid-liquid microextraction methods could be better than other sample preparation protocols in terms of sensitivity, easiness, solvent consumption and waste reduction.