Solvent-free mixed micellar mobile phases: An advanced green chemistry approach for reversed-phase HPLC determination of some antihypertensive drugs

Current green capillary electrophoresis and liquid chromatography methods for analysis of pharmaceutical and biomedical samples (2019-2023) - A review

Separation analytical methods, including liquid chromatography (LC) and capillary electrophoresis (CE), in combination with an appropriate detection technique, are dominant and powerful approaches preferred in the analysis of pharmaceutical and biomedical samples. Recent trends in analytical methods are focused on activities that push them to the field of greenness and sustainability. New approaches based on the implementation of greener solvents, non-hazardous chemicals, and reagents have grown exponentially. Similarly, recent trends are pushed in to the strategies based on miniaturization, reduction of wastes, avoiding derivatization procedures, or reduction of energy consumption. However, the real greenness of the analytical method can be evaluated only according to an objective and sufficient metric offering complex results taking into account all twelve rules of green analytical chemistry (SIGNIFICANCE mnemonic system). This review provides an extensive overview of papers published in the area of development of green LC and CE methods in the field of pharmaceutical and biomedical analysis over the last 5 years (2019-2023). The main focus is situated on the metrics used for greenness evaluation of the methods applied for the determination of bioactive agents. It critically evaluates and compares the demands of the real applicability of the methods in quality control and clinical environment with the requirements of the green analytical chemistry (GAC). Greenness and practicality of the summarized methods are re-evaluated or newly evaluated with the use of the dominant metrics tools, i.e., Analytical GREEnness (AGREE), Green Analytical Procedure Index (GAPI), Blue Applicability Grade Index (BAGI), and Sample Preparation Metric of Sustainability (SPMS). Moreover, general conclusions and future perspectives of the greening procedures and greenness evaluation metrics systems are presented. This paper should provide comprehensive information to analytical chemists, biochemists, and it can also represent a valuable source of information for clinicians, biomedical or quality control laboratories interested in development of analytical methods based on greenness, practicality, and sustainability.

Synthesis of organic solvent-free nitrogen-doped carbon quantum dots as unique green fluorimetric probes for analysis of abrocitinib in human plasma

Atopic dermatitis (AD) is a persistent, inflammatory skin condition that impacts approximately 15 to 20% of children and 1 to 3% of adults globally. Common skin manifestations include papules, papulovesicular, and brown or red patches with swelling, crusting, and flaking. Therefore, the drug abrocitinib (ABR) was approved by the US FDA as an oral treatment for atopic dermatitis. The present study outlines the development of innovative, thermostable, and pH-stable organic solvent-free nitrogen-doped carbon dots (N@CQDs) synthesized through a one-step method for evaluating ABR with a notable quantum yield of 33.84% to minimize the use of organic solvents. Their cost-effectiveness, eco-friendly characteristics, and outstanding photocatalytic properties have established them as a promising alternative to conventional luminescent techniques like fluorescent dyes and luminous derivatization technique. The reaction of ABR with N@CQDs led to a significant decrease in the luminescent response of the produced green and stable carbon quantum dots at 513 nm. The detection range was determined to be 1.0-150.0 ng mL-1, with a lower limit of quantitation (LOQ) equal to 0.52 ng mL-1 based on the linear graph. The green method effectively used for analysis of ABR in pharmaceutical tablets and pharmacokinetic study with high sensitivity.

Design of experiment-oriented development of solvent-free mixed micellar chromatographic method for concomitant determination of metronidazole and ciprofloxacin hydrochloride

A green, fast and robust solvent-free chromatographic method has been developed for concomitant analysis of ciprofloxacin HCl and metronidazole in bulk powder as well as in dosage form using levofloxacin as internal standard (I.S.). Two different designs including fractional factorial (FFD) and Box-Behnken (BBD) designs were implemented for screening and optimization steps, respectively. The optimum chromatographic separation was accomplished using mobile phase composed of 0.13 M sodium dodecyl sulfate and 0.02 M Birij-35 solution adjusted to pH 2.5 using phosphoric acid at a flow rate of 1.3 mL/min and column oven temperature of 40 °C. Chromatographic analysis was performed on X-Bridge (150 mm × 4.6 mm, 5 μm) column with UV detection at 280 nm. A linear response was acquired over the range of 0.4-50 μg/mL for both drugs. The developed method was applied for quantitation of cited drugs in commercially available tablet with mean percent recovery ± SD of 99.45 ± 0.72 and 100.13 ± 0.81 for metronidazole and ciprofloxacin respectively. The method was proven to be green as evaluated by three greenness assessment tools. The run time was 8 min, thus saving time and reagent.

A highly sensitive and green electroanalytical method for the determination of favipiravir in pharmaceutical and biological fluids

BACKGROUND

Favipiravir is currently used for the treatment of coronavirus disease-2019 (COVID-19).

OBJECTIVE

A highly sensitive and eco-friendly electroanalytical method was developed to quantify favipiravir.

METHOD

The voltammetric method optimized a sensor composed of reduced graphene oxide / modified carbon paste electrode in the presence of an anionic surfactant, improving the favipiravir detection limit. The investigation reveals that favipiravir-oxidation is a diffusion-controlled irreversible process. The effects of various pH and scan rates on oxidation anodic peak current were investigated.

RESULTS

The developed method offers a wide linear dynamic range of 1.5-420 ng/mL alongside a higher sensitivity with a limit of detection in the nanogram range (0.44 ng/mL) and a limit of quantification in the low nanogram range (1.34 ng/mL).

CONCLUSION

The proposed method was applied for the determination of favipiravir in the dosage form, human plasma and urine samples. The developed method exhibited good selectivity in the presence of two potential electroactive biological interferants, uric acid which increases during favipiravir therapy and the recommended co-administered vitamin C. The organic solvent-free method greenness was evaluated via the Green Analytical Procedure Index, The present work offers a simple, sensitive and environment-friendly method fulfilling green chemistry concepts.

Green Spectrophotometric Platforms for Resolving Overlapped Spectral Signals of Recently Approved Antiparkinsonian Drug (Safinamide) in the Presence of Its Synthetic Precursor (4-Hydroxybenzaldehyde): Applying Ecological Appraisal and Comparative Statistical Studies

BACKGROUND

Safinamide, a highly specific inhibitor of monoamine oxidase B, is a new approved prodigious therapy used to cure Parkinson's disease (PD).

OBJECTIVE

Before marketing and selling a medicine, manufacturers must guarantee that the manufacturing process is consistent by monitoring levels of process-related chemicals and drug contaminants. Therefore, five precise, fast, and accurate spectrophotometric techniques were employed and evaluated for the simultaneous measurement of safinamide and its synthetic precursor, 4-hydroxybenzaldehyde.

METHODS

The first derivative, derivative ratio, ratio difference, dual wavelength, and Fourier self-deconvolution methods worked well to resolve spectral overlap of safinamide and its synthetic precursor, 4-hydroxybenzaldehyde.

RESULTS

Safinamide detection limits ranged from 0.598 to 1.315 µg/mL, whereas the 4-hydroxybenzaldehyde detection limit was found to be as low as 0.327 µg/mL.

CONCLUSION

According to International Council for Harmonisation (ICH) criteria, all procedures were verified and confirmed to be accurate, robust, repeatable, and precise within reasonable range. No considerable variation was found when comparing the outcomes of the suggested approaches to the findings of previously published methods. The ecological value of established methods was measured: the national environmental methods index (NEMI), the analytical eco-scale, the analytical greenness metric (AGREE), and the green analytical process index (GAPI) were used.

HIGHLIGHTS

This is the first spectrophotometric determination of safinamide drug in the presence of its synthetic precursor. Five simple and efficient spectrophotometric approaches were employed to determine a newly approved antiparkinsonian drug in the presence of its synthetic precursor simultaneously. Ecological appraisal was performed for the developed methods using four assessment tools.

Multi-analyte HPLC–DAD Method for Concurrent Analysis of Six Antimicrobials and Three Proton Pump Inhibitors Frequently used in Management of Helicobacter pylori Infection: Application to Simulated Intestinal Fluid Samples

The present work deals with the optimization, validation and application of a versatile HPLC–DAD method for concurrent estimation of nine antimicrobials and proton pump inhibitors, namely amoxicillin (AMX), doxycycline (DOX), furazolidone (FRZ), lansoprazole (LNS), levofloxacin (LVF), metronidazole (MTZ), omeprazole (OMZ), pantoprazole (PNZ) and tinidazole (TNZ). The selected nine drugs are frequently included in various treatment regimens of Helicobacter pylori infection. Successful separation was accomplished using the analytical column Agilent Zorbax Eclipse plus-C18 (250 × 4.6 mm, 5 µm particle size) and a mobile phase prepared from phosphate buffer pH 5 and acetonitrile pumped at a flow rate 1 mL/min using a gradient elution program. The gradient elution started with buffer/acetonitrile ratio 90:10, then it was altered in 15 min to reach 40:60 by volume. Quantification of the analytes was based on measuring peak areas of AMX at 230 nm, LVF, LNS and PNZ at 290 nm, OMZ at 300 nm, MTZ and TNZ at 320 nm, and DOX and FRZ at 360 nm. The separated compounds eluted at retention times 5.68, 6.43, 7.82, 8.84, 9.42, 10.75, 12.82, 13.74 and 14.90 min for AMX, MTZ, LVF, TNZ, DOX, FRZ, OMZ, PNZ and LNS respectively. Validation of the proposed HPLC procedure was carefully studied according to the ICH items: ranges, precision, accuracy, linearity, robustness and limits of detection and quantitation. The linear dynamic ranges were 5–100, 5–50, 2–40, 10–100, 10–100, 5–50, 2.5–30, 3–30 and 2–30 µg/mL for AMX, MTZ, LVF, TNZ, DOX, FRZ, OMZ, PNZ and LNS, respectively with correlation coefficients > 0.9993. Application fields of the validated method included analysis of laboratory-prepared binary dosage forms along with analysis of several ternary mixtures in spiked simulated intestinal fluid.

Cost-effective, green HPLC determination of losartan, valsartan and their nitrosodiethylamine impurity: application to pharmaceutical dosage forms

Angiotensin-converting enzyme inhibitors are one of the most widely used anti-hypertensive drugs which are used to reduce hypertension. In 2018, the United States Food and Drug Administration together with the European Medicine Agency declared the presence of carcinogenic nitrosamine impurities such as nitrosodiethylamine (NDEA) in some of the products, including valsartan (VLS) and losartan (LOS), and drugs' recall procedures were started. Thus, they should be controlled to be below the acceptable cancer risk level to ensure safety of the pharmaceutical products. Therefore, sensitive and reliable analytical methods were required for detection and quantitation of NDEA in bulk and finished drug products. Green analytical chemistry has received great interest to minimize the amount of organic solvents consumed without loss in chromatographic performance. A green and sensitive HPLC method was developed for the determination of NDEA in LOS and VLS using mobile phase of 0.02 M ammonium acetate adjusted to pH 7.2 and ethanol in gradient manner. Limits of detection and limits of quantification for NDEA were estimated to be 0.2 and 0.5 µg ml^-1, respectively. The standardized limits of NDEA impurity in drug substances were set as 0.56 ppm, which indicates the feasibility of its determination by the proposed conventional method without need for expensive instrumentations (e.g. MS/MS detectors) that are not found in most pharmaceutical quality control laboratories.

Cost-effective, green HPLC determination of losartan, valsartan and their nitrosodiethylamine impurity: application to pharmaceutical dosage forms

Angiotensin-converting enzyme inhibitors are one of the most widely used anti-hypertensive drugs which are used to reduce hypertension. In 2018, the United States Food and Drug Administration together with the European Medicine Agency declared the presence of carcinogenic nitrosamine impurities such as nitrosodiethylamine (NDEA) in some of the products, including valsartan (VLS) and losartan (LOS), and drugs' recall procedures were started. Thus, they should be controlled to be below the acceptable cancer risk level to ensure safety of the pharmaceutical products. Therefore, sensitive and reliable analytical methods were required for detection and quantitation of NDEA in bulk and finished drug products. Green analytical chemistry has received great interest to minimize the amount of organic solvents consumed without loss in chromatographic performance. A green and sensitive HPLC method was developed for the determination of NDEA in LOS and VLS using mobile phase of 0.02 M ammonium acetate adjusted to pH 7.2 and ethanol in gradient manner. Limits of detection and limits of quantification for NDEA were estimated to be 0.2 and 0.5 µg ml^-1, respectively. The standardized limits of NDEA impurity in drug substances were set as 0.56 ppm, which indicates the feasibility of its determination by the proposed conventional method without need for expensive instrumentations (e.g. MS/MS detectors) that are not found in most pharmaceutical quality control laboratories.

Eco-Friendly and Sensitive HPLC and TLC Methods Validated for the Determination of Betahistine in the Presence of Its Process-Related Impurity

Reducing the amounts consumed of organic solvents while keeping good chromatographic performance has been a significant step towards the greening of analytical methodologies. When sodium dodecyl sulfate (SDS) and Brij-35 surfactants are combined in a mobile phase, they can be used as a green alternative to organic modifiers. Surfactants have numerous advantages, including low cost and toxicity, safe environmental disposal, and unique selectivity, in addition to high solubilization capabilities. In this research, two highly selective chromatographic methods were adopted for the determination of betahistine (BHS) in the presence of its pharmacopeial impurity 2-(2-hydroxyethyl)pyridine (HEP). A solvent-free HPLC method was validated, in which the mixture was separated using a C18 column (3.5 µm, 75.0 × 4.6 mm) and a mobile phase composed of 0.01 M Brij-35, 0.12 M SDS, and 0.02 M disodium hydrogen phosphate adjusted to a pH of 5.5 using phosphoric acid. The flow rate was 1.5 mL min−1 and the resolved peaks were detected at 260 nm. Another HPTLC-densitometric method was validated using HPTLC aluminum plates coated with silica gel 60 F254 as the stationary phase and a developing system consisting of methylene chloride/methanol/ethyl acetate/ammonia (at a ratio of 5:2:2:0.2 by volume); the separated bands were scanned at 260 nm.

Green Stability Indicating Organic Solvent-Free HPLC Determination of Remdesivir in Substances and Pharmaceutical Dosage Forms

A green liquid chromatographic method is considered in this work to minimize the environmental impact of waste solvents. One important principle is to replace or eliminate the use of hazardous organic solvents. Organic impurities in any active pharmaceutical ingredient could arise either during the process of its synthesis, or as degradation products developed throughout the shelf-life. Remdesivir (RDS) is an antiviral drug, approved by the US Food and Drug Adminstration (-FDA), to treat SARS-Cov-2 virus during its pandemic crisis. We studied the stability of remdesivir against several degradation pathways using the organic solvent-free liquid chromatographic technique. Separation was performed on RP-C18 stationary phase using mixed-micellar mobile phase composed of a mixture of 0.025 M Brij-35, 0.1 M sodium lauryl sulfate (SLS), and 0.02 M disodium hydrogen phosphate, adjusted to pH 6.0. The mobile phase flow rate was 1 mL min−1, and detection was carried out at a wavelength of 244 nm. We profiled the impurities that originated in mild to drastic degradation conditions. The method was then validated according to International Conference of Harmonization (ICH) guidelines within a linearity range of 5–100 μg mL−1 and applied successfully for the determination of the drug in its marketed dosage form. A brief comparison was established with reported chromatographic methods, including a greenness assessment on two new metrics (GAPI and AGREE). This study is the first to be reported as eco-friendly, solvent-free, and stability indicating LC methodology for RDS determination and impurity profiling.

Sweeping-micellar electrokinetic chromatography versus reversed phase liquid chromatography for the determination of coumarin in curry

Coumarin is a phytotoxin found in the popular spice cinnamon, which is used to flavor many Asian curry dishes. In this work, we developed and compared the analytical performance of reversed-phase liquid chromatography (RP-LC) and sweeping-micellar electrokinetic chromatography (MEKC) methods for the determination of coumarin in complex curry (gravy) samples. Using a matrix matched sample (curry after solvent extraction with methanol and diluted with 100 mM phosphoric acid), the intra-day and inter-day repeatability of retention/migration time and (corrected) peak area for both methods were acceptable (%RSD (n=6) ≤ 5%). The linear range and limit of quantitation (LOQ) were an order of magnitude better in RP-LC (RP-LC linear range = 0.11-108 mg/kg, LOQ = 0.11 mg/kg) (Sweeping-MEKC linear range = 2.16-216 mg/kg, LOQ = 2.16 mg/kg). However, the limit of detection (S/N=3) and LOQ in sweeping-MEKC was 0.65 mg/kg and 2.16 mg/kg, which were sufficient to report the levels of coumarin ≥ the European limit of 2 mg/kg in foods. During the analysis of 25 curry samples, relatively similar results for sweeping-MEKC and RP-LC were obtained for 6 samples that contained coumarin >LOQ of sweeping-MEKC. Interferences in RP-LC lead to significant overestimation of coumarin levels in 3 samples. Coumarin levels above the EU limit was found in 6 curry samples using the more selective sweeping-MEKC. This work should also raise public awareness on the presence of potentially high levels of coumarin in some foods.

Quantitative analysis of nine isoflavones in traditional Chinese medicines using mixed micellar liquid chromatography containing sodium dodecylsulfate/β-cyclodextrin supramolecular amphiphiles

Isoflavone is one of the phytoestrogens that have estrogenic effects, so it is usually served as an active ingredient for quality control of traditional Chinese medicines rich in isoflavones. Nine isoflavones commonly found in traditional Chinese medicines were separated in 30 min using mixed micellar liquid chromatography. The mobile phase consisted of 0.08 M sodium dodecylsulfate and 6.05 mM β-cyclodextrin:methanol (87:13, v/v) at pH 3 and eluted isocratically at 1 mL/min through a C18 column. In this study, we systematically optimized the chromatographic conditions including the pH, the composition and concentration of surfactants, the type and ratio of organic solvents, and column temperature. The method was validated according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use guidelines. There is no report using micellar liquid chromatography to detect isoflavones, and the optimized method has been successfully applied to quantify isoflavones in red clover and Radix Puerariae. This method is efficient, cheap, and convenient. Finally, we verified the existence of supramolecular amphiphilic vesicles in the mobile phase by transmission electron microscopy to explain the increased chromatographic efficiency.

Determination of six drugs used for treatment of common cold by micellar liquid chromatography

The use of organic solvents as eluants in RP-HPLC has an important role to decrease retention time and improve peak shape; however, it has high environmental impacts. Their production and disposal represent economic and biohazard problems. So, alternatives had to be introduced and studied to minimize such pollution. Combination of sodium dodecyl sulfate (SDS) together with polyoxyethylene-23-lauryl ether (Brij-35) was studied as an alternative to the presence of organic solvents on the separation performance of six active pharmaceutical ingredients. Response surface methodology was applied to test the impact of three independent variables; concentrations of SDS and Brij-35, as well as, pH of the mobile phase; on retention, peak symmetry, and resolution of the analytes using a rotatable central composite design. Significant variables were determined and the suggested models for predicting retention and resolution parameters were significant. Meanwhile, the common cold is the most abundant disease treated with over-the-counter (OTC) medications worldwide. In 2015, the USA recorded $9.56 billion total sales of OTC cold and cough medicaments alone, with average individual patient expenditure of $338. The worldwide sales and generics of common cold and cough products keep growing annually. The six active pharmaceutical molecules under study, namely, paracetamol, guaifenesin, pseudoephedrine, ibuprofen, chlorpheniramine, and dextromethorphan, are widely used in common cold products. The predicted optimum conditions were validated using mobile phase consisting of 93.6 mM SDS, 32.0 mM Brij-35, and 10.0 mM sodium dihydrogen phosphate, adjusted at pH 5.2, column temperature 35° C, and detection at 215-nm wavelength. The method was successfully applied to determine 12 different combination formulae of the analytes in their pharmaceutical products and was assessed for greenness on two novel metrics. A thorough comparison to previously reported methods was included and methods were assessed against greenness metrics Green Analytical Procedure Index and Analytical Greenness Metric to demonstrate superiority.

Green micellar solvent-free HPLC and spectrofluorimetric determination of favipiravir as one of COVID-19 antiviral regimens

Quality control (QC) of pharmaceutical products requires fast, sensitive as well as economic methodologies in order to provide high through output at low cost which are the main aspects considered by such economic facilities. Meanwhile, the ecological impacts must be considered by researchers to minimize the hazardous effects of research laboratories. Favipiravir (FAV) is an antiviral agent recently approved for treatment of COVID-19 infections during 2020 pandemic crisis, so the size of its production by international pharmaceutical corporations evolved dramatically within the past few months. Two novel simple, sensitive, and green methods were developed and validated for FAV determination based on solvent-free micellar LC and spectrofluorimetry techniques. To improve FAV native fluorescence, several factors were studied including solvent type, buffering, pH and added surfactants. The best sensitivity for FAV fluorescence was obtained in Britton-Robinson buffer (pH 4) at 436 nm after excitation at 323 nm within concentration range of 20-350 ng mL-1. Another HPLC method was validated using C18-RP (5 µm, 250 × 4.6 mm) stationary phase and solvent-free mobile phase consisting of (0.02 M Brij-35, 0.15 M SDS, and 0.02 M disodium hydrogen phosphate, pH 5.0) isocratically eluted at a flow rate of 1 mL min-1 and detection wavelength of 323 nm. LC method was validated across concentration range of 10-100 µg mL-1 and FAV eluted in 3.8 min. The methods were validated according to the FDA guidelines and were applied successfully for determination of FAV in its marketed tablet dosage forms and in spiked human plasma samples. The proposed methods are eco-friendly since they are typically based on biodegradable reagents in aqueous solvent-free phases, which was proven by their assessment on two recent greenness metrics (GAPI and AGREE) to prove their eco-friendly properties.