HPLC Approach Research Articles

A fluorescence biosensor for organophosphorus pesticide detection with a portable fluorescence device-based smartphone

An innovative fluorescence biosensor was successfully developed to detect organophosphorus pesticide (OPs) by utilizing smartphone technology. The assay relied on the enzymatic activity of alkaline phosphatase (ALP), which facilitated the conversion of L-ascorbic acid 2-phosphate sesquimagnesium salt hydrate (AAP) into L-ascorbic acid (AA). The AA that generated was then reactedwith o-phenylenediamine (OPD) to yield a fluorescent marker identified as 3-(1,2-dihydroxyethyl)furo[3,4-b]quinoxalin-1(3H)-one (DFQ). A novel bandpass approach was specifically developed for a smartphone that was integrated with a customized portable fluorescence device to measure the fluorescence emission of DFQ. The device has a unique application that converts the fluorescence intensity into an RGB signal. In the presence of OPs, malathion was chosen as the representative of the OPs substance; the enzymatic activity of the ALP was inhibited, resulting in a decrease in fluorescence intensity, which was proportional to the concentration of malathion. Smartphones can be used to measure fluorescence emission, offering a calibration sensitivity more than 70 times higher than that of conventional spectrofluorometer. The recently developed methodology can be employed to identify malathion within the concentration range of 0.1–1 ppm, with a detection limit of 0.05 ppm. The practical applicability of the method was established using vegetable samples, and the acquired results were in good agreement with those obtained using the standard HPLC approach. This innovative method provides both portability and accuracy, while also exhibiting a notable degree of sensitivity in detecting traceamounts of OPs.

Efficient integration of analytical quality-by-design and tri-hued HPLC-DAD approach for synchronized assessment of gemigliptin and rosuvastatin in their fixed-dose pills: Application to stability study

Life-threatening atherosclerotic cardiovascular disorder is a well-recognized risk among diabetics, which is clinically ascribed to their unbalanced plasma lipoproteins. Gemigliptin-Rosuvastatin is a recently introduced polytherapy prescribed for the management of diabetic dyslipidemia. Currently, the main focus of several analysts is to design more ecologically friendly sustainable approaches for pharmaceutical analysis. In this context, an innovative tri-hued (green, blue, and white) stability-indicating HPLC-DAD approach was developed to concurrently quantify Gemigliptin and Rosuvastatin polypills. Consequently, a strategic integration between analytical quality-by-design and green/white analytical chemistry principles was specifically designed to optimize efficiency and practicality while minimizing ecological burden. Two experimental designs, namely two-level fractional factorial and Box-Behnken designs, were employed for screening and optimization procedures, respectively. Optimal separation was attained utilizing an Agilent HC-C18 column in conjunction with a mobile phase consisting of acetonitrile and 10 mM sodium dihydrogen phosphate buffer, pH 3 (60:40 v/v), eluted in an isocratic manner at a 1 mL/min flow rate. Both analytes exhibited good linearities within the concentration range of 0.5–100 μg/mL. Furthermore, stability studies were conducted on both drugs in response to variable stress degradation scenarios. Fortunately, the adopted approach was well-suited to resolve the studied drugs from their respective degradants, thereby verifying the method's stability-indicating power. Tri-hued evaluation for the implemented approach was performed via up-to-date metrics, specifically, the Analytical Eco-scale, AGREE, Blue Applicability Grade Index, and RGB 12. Ultimately, our adopted stability-indicating HPLC approach exhibited great sensitivity, specificity, applicability, and rapidity as well as being ecologically sound. It is worth noting that this is the first stability-indicating HPLC approach for simultaneous assessment of the studied drugs.

A novel QbD HPLC approach for the concurrent analysis of amoxicillin, amprolium, and ethopabate in food samples and dosage forms

A simple, rapid, and sensitive reversed-phase HPLC method coupled with photodiode array detection (PDA) was developed for the simultaneous estimation of three co-administered antibacterial drugs, amprolium, ethopabate, and amoxicillin for the first time. An analytical quality-by-design (QbD) approach was adopted to optimize the developed approach. A two-level full factorial design (25 FFD) was implemented to optimize how variable factors affected chromatographic responses. On a Hypersil BDS C18 column, the chromatographic separation was carried out using isocratic elution at 40.1 °C. The mobile phase consisted of methanol: potassium phosphate buffer containing 5.76 mM heptane sulphonate (9.05 mM; pH 3.32, 44.8:55.2 % v/v) pumped at a flow rate of 0.8 mL/min and an injection volume of 20.0 μL. In less than 7 min, the suggested method was able to separate the ternary mixture with a challenging ratio of 1: 15.6: 1 for amoxicillin, amprolium, and ethopabate, respectively. The calibration curves showed excellent linearity over the concentration ranges of 0.50–30.0, 0.30–30.0, and 0.05–20.0 μg/mL, respectively. Recovery percentages ranged from 90.30 % to 111.13 % with %RSD less than 2 % were obtained upon spiking to chicken tissues, liver, and egg samples, indicating the suitability of the proposed method for determining of the studied drugs in complicated food matrices. Furthermore, the proposed method was successfully applied to determine the studied drugs in their commercial formulations. Full validation was carried out according to ICHQ2 (R1) guidelines. Finally, the method's greenness and ecofriendliness were evaluated using various metrics tools, including the Green Analytical Procedure Index (GAPI) and Analytical GREEnness (AGREE).

(Invited) Metallofullertubes or Metallofullerenes: Which Have We Isolated?

In our labs, we are isolating several novel carbon-metal endohedral molecules of unknown structures with rare-earth metals. In this presentation, we will discuss the feasibility of using chemical reactivity differences (Round 1) to obtain samples enriched in their presence. Next, using a multiple column HPLC approach for further resolution (Round 2), we have isolated and begun a preliminary characterization (e.g., UV-vis) for these pristine samples. We know their chemical formulas, but we do not yet know the structural arrangement of metal and carbon atoms. When sufficient quantities are obtained, we will pursue X-ray crystallography to address the following big question. Namely, do we have metals in tubes (metallofullertubes) or do we have metals in big balls (metallofullerenes). An objective of this presentation is to update and share with the fellow scientific community our most recent advances and progress in the research area of larger carbon cage structural housings (e.g., C96-C120).

A stability-indicating HPLC assay of ten different vitamins in a food supplement: Appraisal of the method's greenness, whiteness, and blueness

Due to their susceptibility to degradation, vitamin levels in food formulations may differ from those found in the finished product. Vitamin levels can be impacted by processing and storage. In this work, the ingredients of Strong B50 ® film-coated tablets were estimated simultaneously using simple efficient stability indicating HPLC method. Strong B50 ® film-coated tablets contain thiamine (VB1), riboflavin (VB2), calcium pantothenate (VB5), pyridoxine (VB6), vitamin C (VC), folic acid (FA), biotin (BT), inositol (IS), niacin (NC), para-aminobenzoic acid (PB), cyanocobalamine (B12), choline bitartarate, and iron gluconate. Hypersil BDS C18 column was used for achieving reasonable separation. Mobile phases (A) and (B) were utilized, the mobile phase (A) consisted of 0.015 M Hexane sulfonic acid sodium salt + 0.1 % Triethylamine and orthophosphoric acid was used to adjust the pH to (2.9) while (B) system consisted of acetonitrile. Validation of the method was assessed using International Conference of Harmonization (ICH) parameters, where linearity, accuracy, selectivity, and robustness of the method were investigated. Correlations were above 0.99, accuracy results ranged from 97.6 to 102.8 % and limits for detection and quantitation (LOD and LOQ) values were determined for each vitamin in μg/mL except for FA and BT in ng/mL. LOD values were between 0.006 and 15.08 μg/mL while LOQ values ranged from 0.031 to 49.77 μg/mL. Stability studies were conducted under stressed conditions and degradation percentages were computed. Where, VB5, VB6, FA and PB, VC, and NC were the most degradable vitamins. Whiteness evaluation using the modern RGB 12 algorithm compared our method and the old reported one by Sasaki et al., 2020. The comparison favored our newly developed method in terms of analytical performance, practical applicability and greenness. Besides, AGREE and GAPI soft wares were used to assess the greenness of the method. It was clear that the results of colored pictograms confirm low hazardous impact and that the new method is greener with AGREE score of 0.66. Furthermore, the functionality and applicability of the novel HPLC approach were concluded via the Blue Applicability Grade Index (BAGI) tool with a final score of 82.5.

A Green HPLC Approach to Florfenicol Analysis in Pig Urine.

Florfenicol (FF) is a broad-spectrum antibiotic used to treat gastrointestinal and respiratory infections in domestic animals. Considering FF's rapid elimination via urine after drug treatment, its use increases concerns about environmental contamination. The objective of the study was to establish a sustainable chromatographic method for simple analysis of FF in pig urine to investigate the urinary excretion of FF after a single intramuscular administration of 20 mg FF/kg body weight. The urine sample was prepared using a centrifuge and regenerated cellulose filter, and the diluted sample was analyzed. The method was validated in terms of linearity, the limit of detection (0.005 µg/mL) and quantitation (0.016 µg/mL), repeatability and matrix effect (%RSD ranged up to 2.5), accuracy (varied between 98% and 102%), and stability. The concentration-time profile of pig urine samples collected within 48 h post-drug administration showed that 63% of FF's dose was excreted. The developed method and previously published methods used to qualify FF in the urine of animal origin were evaluated by the National Environmental Method Index (NEMI), Green Analytical Procedure Index (GAPI) and Analytical GREENness Metric Approach (AGREE). The greenness profiles of published methods revealed problems with high solvents and energy consumption, while the established method was shown to be more environmentally friendly.

Development of HPLC Approach for Anticancer Drugs Combination Assay: Determination of Stability Indicating Quality and Stabilities of Anticancer Drugs Studied under the ICH Outlined Degrading Conditions

Development of HPLC Approach for Anticancer Drugs Combination Assay: Determination of Stability Indicating Quality and Stabilities of Anticancer Drugs Studied under the ICH Outlined Degrading Conditions

Design of Experimental Approach for Development of Rapid High Performance Liquid Chromatographic Process for Simultaneous Estimation of Metoprolol, Telmisartan, and Amlodipine from Formulation: Greenness and Whiteness Evaluation.

The design of an experimental approach, the Box-Behnken design, was implemented to optimize the chromatographic condition to develop a rapid HPLC procedure for quantification of a ternary mixture of metoprolol (MET), telmisartan (TEL), and amlodipine (AML) from the formulation. The perturbation plots, contour, and 3D response surface pictures were developed to study the impact of each variable on the analytes' retention time and the probable interaction between the parameters with fewer chromatographic runs. The optimized HPLC method separated the three analytes within 5 min with excellent selectivity and peak shape on a Zorbax C18 HPLC column using acetonitrile and phosphate buffer (20 mM, pH 5.8) with isocratic elution at a 1.1 mL/min flowrate. A wavelength 230 nm was utilized to monitor the elute. The validation of proposed method demonstrated a wide linearity range of 10-200 µg/mL for MET and TEL and 5-50 µg/mL for AML along with an excellent correlation coefficient. The correctness of the HPLC approach was further confirmed by excellent recovery of the added amount of analytes utilizing the standard addition technique. The recommended HPLC approach was employed safely for quality assurance of the formulation, because the evaluation of the method's greenness and whiteness confirmed the environmentally friendly nature of the approach.

A Robust HPLC Approach for Quantitation of Camptothecin in Mesoporous Silica Nanoparticles Matrix and in the Presence of Its Degradation Products.

Camptothecin is a potent anticancer drug used for the treatment of various cancers. The goal of this research investigation was to develop and validate a new stability-indicating HPLC technique for the quantitative assessment of camptothecin in in-house developed mesoporous silica nanoparticles, a novel nanoformulation matrix for the treatment of cancer. The Waters Inertsil® HPLC column (C18) was used for the chromatographic separation, with a flow rate of 1 mL/min, a column oven temperature of 40°C, an injection volume of 10 µL, a detection wavelength of 216 nm, and a 10 min runtime overall. An isocratic blend of phosphate buffer (10 mM, pH7.0) and acetonitrile (60:40, v/v) served as the mobile phase. Various stress conditions including acid, alkali, oxidative, photolytic, thermal, and humidity environments were tested for the quantitative estimation of the camptothecin through the proposed method. The results demonstrated that the proposed method is specific (peak purity ≥0.999), accurate (99.69-100.64% w/w), precise (RSD, % <2.0), and sensitive (LOD-0.17 µg and LOQ-0.56 µg) in accordance with ICH guideline Q2 (R1). Any unidentified degradation products did not interfere with the drug's estimation. Furthermore, the current method of analysis has eliminated any excipient interference from the matrix effect caused by the numerous excipients of the formulation matrix. To quantify camptothecin for routine assay purposes, this research work offers a novel and straightforward HPLC methodology with optimized chromatographic parameters, contributing to the research and development community while ensuring an appropriate and efficient use of the drug through a variety of nanoformulation for cancer treatment. The stability-indicating HPLC method was found to be specific and suitable for routine analysis of camptothecin. The absence of any interference from excipients was confirmed by forced degradation studies.

HPLC method for simultaneous quantification of lumacaftor and ivacaftor bulk and pharmaceutical formulations

In 2015, the Food and Drug Administration granted approval for the use of lumacaftor 200 mg and ivacaftor 125 mg in the treatment of cystic fibrosis patients who possess the F508del mutation, namely those who are 12 years of age or older. Since its approval, the medicine has been implemented in clinical settings, although the presence of numerous disputes, with the aim of mitigating disease symptoms and enhancing the overall quality of life. Given the existing gaps in the literature regarding the analysis of the amalgamation of these two active substances, a straightforward and practical HPLC approach has been devised in adherence to the guidelines outlined in the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2(R1) document. To accomplish this objective, the process of separation was successfully carried out using a monolithic silica stationary phase (Chromolith High Resolution RP-18e, 100 mm × 4.6 mm i.d., Merck KGaA, Darmstadt, Germany). The separation process was conducted using a gradient mode. The initial composition of the mobile phase consisted of acetonitrile and a phosphate buffer solution with a concentration of 0.030 M and a pH of 3.5. The flow rate was recorded as 1.0 mL/min, and avanafil was used as an internal standard. The improved and verified approach has demonstrated successful application in bulk and pharmaceutical formulation evaluations when utilizing the ivacaftor/lumacaftor combination.

High-temperature ultrafast ChipHPLC-MS

Herein, we present a miniaturized chip-based HPLC approach coupled to electrospray ionization mass spectrometry utilizing temperature to achieve high-speed separations. The approach benefits from the low thermal mass of the microfluidic chip and can form an electrospray from the pre-heated mobile phase. With the help of this technology, isothermal and temperature-programmable operations up to 130°C were pursued to perform reversed-phase separations of pesticides in methanol and ethanol-containing eluents in less than 20 s.Graphical

Optimization of ultrasound-assisted extraction of glycyrrhizic acid and glabridin from Glycyrrhiza glabra L. using response surface methodology and development of a green analytical method

In this study, ultrasound assisted extraction (UAE) were used to investigate the extraction of glycyrrhizic acid (GA) and glabridin (GD) simultaneously from Glycyrrhiza glabra L. and a green HPLC analytical approach for determining GA and GD was developed. Extraction pocess were optimizing by Response surface methodology (RSM) utilizing Box-Behnken design (BBD). According to the consequences, the ideal extraction situations were: 64% (v/v) ethanol concentration, 22 mL/g liquid-solid ratio, 51 °C and 31 min. Under these conditions, the yields of GA and GD were 2.806 ± 0.107% and 0.252 ± 0.026%, respectively, and the actual experimental extraction values were fundamentally the same as the anticipated values. Meanwhile, the effects of UAE, maceration (MAC) and heat-reflux extraction (HRE) on yeild were assessed, and the UAE possessed highest yields. A green HPLC approach was created to analyze GA and GD with combinations of ethanol and a 0.1% (v/v) trifluoroacetic acid mobile phase (following the gradient elution method). The method validated based on the guidelines of the International Conference on Harmonization (ICH) and the result indicated the method was precise, stable, reliable and valuable, could be used to analyze GA and GD from Glycyrrhiza glabra L.

Eco-friendly micellar HPLC approach for simultaneous estimation of combination therapy for hidradenitis suppurativa: Applications to spiked human plasma and different dosage forms.

This study introduces a new method for analyzing rifampicin, moxifloxacin, and metronidazole using a green micellar High Performance Liquid Chromatography-Ultraviolet method in bulk drugs, different commercial formulations, and spiked human plasma. The combined therapy of these three broad-spectrum antibiotics is used to cure refractory hidradenitis suppurativa (HS), an inflammatory condition affecting the skin. The sustainable separation was attained on a reversed-phase C18 Kinetex® column maintained at ambient temperature in less than 5 min. The mobile phase comprises 0.1 M sodium dodecyl sulfate (SDS) in water, pH 3.5, adjusted using o-phosphoric acid, and 10% n-butanol. The flow rate was 1 mL/min, with 10 μL injection volume and UV detection at 230 nm. The impact of three key significant variables, SDS concentration, n-butanol percentage, and the mobile phase pH, on suitability parameters was studied. ICH and FDA guidelines were committed to when validating the technique. The results showed linear calibration graphs with high precision and accuracy, in both pure and spiked plasma. The method is efficient, easy to use, and has a high sample throughput, making it suitable for routine analysis in the quality control department and therapeutic monitoring. It is also evaluated as a green-and-white substitute for traditional reported methods.

Development, Optimization, and Validation of a RP-HPLC Method with PDA Detection for the Concurrent Quantification of Emtricitabine, Tenofovir Alafenamide, and Dolutegravir in Both Bulk and Pharmaceutical Dosage Forms

A simple, quick, precise and accurate HPLC (reverse phase) approach has been designed and optimized using a chemometric tool to estimate dolutegravir, emtricitabine and tenofovir alafenamide, respectively. A design of central composite was used to optimize the response surface. As a result of trial and error, the parameters such as rate of solvent flow, buffer pH, and methanol concentration in the solvent system were determined. System responsiveness was estimated using the optimization process’s capacity factor, resolution, and retention time. The separation was achieved by using a solvent system containing 58.90% methanol and 41.10 triethylamine buffer (4.56 pH) at the rate of flow of 0.8 mL per minute on a phenomenex carbon (18) column (150.4 4.6 mm; I.D., 5) under optimal conditions. The duration of retention for emtricitabine was 2.91 minutes, for tenofovir alafenamide it was 6.114 minutes; and for dolutegravir it was 8.824 minutes. A correlation coefficient of 0.9998, 0.9997, and 0.9999 was determined for emtricitabine’s calibration curves from 40 to 200 g/mL, tenofovir alafenamide’s from 5 to 25 g/mL, and emtricitabine’s from 10 to 50 g/mL, respectively. This approach was effective in estimating the simultaneous doses of medications in commercial combination forms

Eco-friendly micellar HPLC approach for assessment of two anti-asthmatic breezhalers; Application of central composite design

Short-term breathing problems are brought on by asthma, a chronic lung disease. Mometasone furoate (MOF) and Indacaterol (IDT), are co-formulated alone or with Glycopyrronium (GLY) in the form of inhalation powder to control the symptoms of asthma. A novel green hybrid micellar liquid chromatographic method was developed to analyze the three mentioned medications. Contrary to routine analysis, Quality by Design methodology was applied to maximize the resolution with the fewest number of trials. Fractional factorial design was used to study the impact of three significant variables: sodium dodecyl sulphate (SDS) concentration, methanol %, and the mobile phase pH. Separation of the analytes was optimized by central composite design using a mobile phase consists of (191.49 mM) SDS and (10.00 mM) potassium dihydrogen phosphate buffer: methanol (77.50: 22.50 v/v), pH 3.00 on a reversed phase C18 column, within eight minutes. The flow rate was 1.2 mL/min, with 20 µL injection volume, and UV detection at 210 nm. Green Analytical Procedure Index, and Analytical Greenness Calculator were used for the method’s greenness evaluation, and it was deemed to be an effective green methodology. The developed approach was effectively applied for quantitative determination of the three drugs in bulk powder and two pharmaceutical dosage forms. International Conference of Harmonization requirements were adhered to when validating the approach. Under optimized conditions, calibration curves of the studied drugs were linear over the concentration range of (10.00 – 100.00 µg/mL) with high accuracy results and correlation coefficients of 0.9997 for MOF, 0.9996 for IDT and 0.9996 for GLY. Additionally, a precise approach has been demonstrated by the intra- and inter-day coefficients of variation ≤ 2%. The LOD and LOQ were (2.39 μg/mL) and (7.25 μg/mL) for MOF, (2.67 μg/mL) and (8.08 μg/mL) for IDT, and (2.80 μg/mL) and (8.48 μg/mL) for GLY, respectively.

A Turn-Off Fluorescent Biomimetic Sensor Based on a Molecularly Imprinted Polymer-Coated Amino-Functionalized Zirconium (IV) Metal-Organic Framework for the Ultrasensitive and Selective Detection of Trace Oxytetracycline in Milk.

Developing sensitive and effective methods to monitor oxytetracycline residues in food is of great significance for maintaining public health. Herein, a fluorescent sensor (NH2-UIO-66 (Zr)@MIP) based on a molecularly imprinted polymer-coated amino-functionalized zirconium (IV) metal-organic framework was successfully constructed and first used for the ultrasensitive determination of oxytetracycline. NH2-UIO-66 (Zr), with a maximum emission wavelength of 455 nm under 350 nm excitation, was prepared using a microwave-assisted heating method. The NH2-UIO-66 (Zr)@MIP sensor with specific recognition sites for oxytetracycline was then acquired by modifying a molecularly imprinted polymer on the surface of NH2-UIO-66 (Zr). The introduction of NH2-UIO-66 (Zr) as both a signal tag and supporter can strengthen the sensitivity of the fluorescence sensor. Thanks to the combination of the unique characteristics of the molecularly imprinted polymer and NH2-UIO-66 (Zr), the prepared sensor not only exhibited a sensitive fluorescence response, specific identification capabilities and a high selectivity for oxytetracycline, but also showed good fluorescence stability, satisfactory precision and reproducibility. The fabricated sensor displayed a fluorescent linear quenching in the OTC concentration range of 0.05-40 μg mL-1, with a detection limit of 0.012 μg mL-1. More importantly, the fluorescence sensor was finally applied for the detection of oxytetracycline in milk, and the results were comparable to those obtained using the HPLC approach. Hence, the NH2-UIO-66 (Zr)@MIP sensor possesses great application potential for the accurate evaluation of trace oxytetracycline in dairy products.

Systematic Selection of Impurities, Development, and Validation of Related Substance Methods for Estradiol and Progesterone in a Combination Drug Product.

A kind of estrogen called estradiol is a female sex hormone that regulates several body processes. In hormone replacement therapy for women, the endogenous steroid progesterone is employed. The soft gel capsule medication, which contains a mix of 1 mg estradiol and 100 mg progesterone, is used to treat moderate to severe menopause symptoms, such as hot flashes, in women who have uteruses, as well as feelings of warmth in the face, neck, and chest. To establish the stability of drug products in accordance with the ICH Harmonized Tripartite Guideline, Stability Testing of New Drug Substances and Products (Q1A), this study aims to develop a reverse-phase chromatographic method, the necessary analytical methodology for identifying the drug degradation profiles. The procedures were optimized using a C18 column (250 × 4.6 mm, 5 µ) as the stationary phase and conventional solvents such as water-acetonitrile mixtures as the mobile phase. A quantification technique had been an HPLC combined with a UV/PDA and fluorescence detector. The developed methods for both estradiol and progesterone were capable of all components of each active individually by overcoming the extremely difficult challenges of a combination product with similar structural compounds, having 24 impurities in all, and having complex excipients used for soft gel formulation. The method has been successfully created, validated for use in compliance with regulatory specifications, and determined to be accurate, linear, specific, and stability-indicating in nature. To quantify the associated impurities of both actives in the presence of a highly complex matrix, the performance of the HPLC approach considerably possesses a higher degree of selectivity.

Green quality by design HPLC approach for the simultaneous determination of Bilastine and Montelukast

For the simultaneous estimation of two co-formulated antihistaminic drugs (Bilastine and Montelukast), a novel and eco-friendly reversed-phase HPLC approach with both diode array and fluorescence detection modes was designed. Rather than using the routine methodology, the Quality by Design (QbD) approach was adopted to speed up the method development and to test robustness of the method. To evaluate the effect of variable factors on chromatographic response, a full factorial design was used. The chromatographic separation was performed using isocratic elution on the C18 column. The mobile phase consists of 92% methanol, 6% acetonitrile, and 2% phosphate buffer with 0.1 (v/v) triethylamine adjusted to pH 3, it was pumped at a flow rate of 0.8 mL/min with an injection volume of 20 μL. The developed stability indicating HPLC approach was used to assess the stability of montelukast (MNT). It was subjected to a variety of stress conditions, including hydrolytic (acid–base), oxidative, thermal, and photolytic stress conditions. All of these conditions were found to have relevant degradation pathways. Under the described experimental conditions, MNT degradation followed pseudo-first-order kinetics. The kinetic parameters of its degradation (rate constant and t1/2) were calculated and a proposal for the degradation pathway was postulated.

Flexible SERS sensor using AuNTs-assembled PDMS film coupled chemometric algorithms for rapid detection of chloramphenicol in food

The misuse of chloramphenicol (CAP) has led to the development of drug-resistant strains that pose significant threats to public health. Here, we propose a universal flexible surface-enhanced Raman spectroscopy (SERS) sensor utilizing gold nanotriangles (AuNTs) and polydimethylsiloxane (PDMS) film for rapid detection of CAP in food samples. Initially, AuNTs@PDMS with unique optical and plasmonic properties were used to collect spectra of CAP. Afterward, four chemometric algorithms were executed and compared. Accordingly, random frog-partial least squares (RF-PLS) exhibited optimum results with correlation coefficient of prediction (Rp = 0.9802) and the lowest root-mean-square error of prediction (RMSEP = 0.348 µg/mL). Furthermore, the sensor's efficacy to detect CAP in milk samples was confirmed, and the findings were compatible with the conventional HPLC approach (P > 0.05). Therefore, the proposed flexible SERS sensor could effectively be used to monitor milk quality and safety.

Development of Stability Indicating RP-HPLC Method for Tizanidine Hydrochloride in Bulk Drug and Pharmaceutical Dosage Form

The quantitative analysis of tizanidine hydrochloride in both pharmaceutical dosage form and bulk medication has been developed and validated using an easy, affordable, quick, and unique isocratic HPLC approach. Tizanidine hydrochloride was separated isocratically using Waters symmetry C18 ODS as the stationary phase (250×4.6 mm, 5μm particle size), a flow rate of 1.0 ml/min, and a UV detector to track the eluate at 230 nm. The drug and its degradation products could be separated using the mobile phase, which was made up of acetonitrile: phosphate buffer (20:80 v/v) and pH-adjusted to 3.0 by ortho-phosphoric acid. Linearity, accuracy (recovery), precision, specificity, and robustness of the approach were all validated. For the range of 4-80 μg/ml, the linearity of the technique was satisfactory (correlation coefficient 0.999). Between 100.4 to 101.3% of the tizanidine hydrochloride was recovered from the medicinal dosage form. In order to analyze the samples, tizanidine hydrochloride was put under stress conditions, including hydrolysis (acid, base), oxidation, photolysis, and heat degradation. The tizanidine hydrochloride forced degradation study demonstrated that it decomposed under minimal conditions. Under the other stress scenarios examined, the medication remained steady. It was discovered that tizanidine hydrochloride was significantly more stable in its solid state than in its solution condition. The breakdown products were clearly distinguishable from the primary peak. The validation method may be useful for routine analysis of tizanidine hydrochloride as bulk drug, in respective dosage forms, for dissolution studies, and as a stability indicating assay method in pharmaceutical laboratories and industries because the forced degradation study proves the method's stability indicating power.&#x0D; Keywords: RP-HPLC, Tizanidine hydrochloride, Forced degradation, Method validated