## Spectrophotometric Determination of Remdesivir and Molnupiravir in Binary Mixture
In the present study, six simple and sensitive spectrophotometric methods where suggested for the selective quantitative determination of RDV and MFX without previous separation.
### Spectral characteristics
The zero-order absorption spectra of RDV and MFX show severe overlap, as shown in fig. 2 which does not permit direct determination of RDV and MFX presence of each other.
So, three proposed ratio methods are based on dividing the absorption spectra of each drug by the absorption spectrum of second drug, as a divisor, to get the ratio spectra, were used as shown in Figures (3, 4).
### Ratio derivative method
for RDV and MFX, respectively, the amplitudes of the first derivative of the ratio spectra at 250 nm and 290 nm are proportional to the concentrations of each medication independent of the other (divisor), as illustrated in Figures 5, 6, 7, 8.
### Ratio difference method
Without interference from the second medication (divisor), the ratio spectra’s peak amplitudes between (247-262) nm and (299-313) nm are proportionate to the RDV and MFX concentrations, respectively.
### Mean centering method
Mean-centered ratio spectra were obtained. Without the other drug interfering, the mean centered values at 247 nm and 299 nm are proportional to the concentrations of RDV and MFX, respectively, as illustrated in Figures 9, 10.
other three methods were also used including:
### Area under the curve method
Figure 11 lists the area under the curves for RDV and MFX,respectively,over the ranges of (243-248) and (290-300) nm. We created the calibration graphs and calculated the regression equations that connect the measured areas under the curve to the concentration of each component in µg/ml.The concentrations of RDV and MFX were steadfast using Eqs. (1) and (2), respectively, based on the absorptivity values and areas under the curve for each component at the chosen wavelength ranges.
### Q-analysis method
The absorption spectra of RDV and MFX showed isoabsorptive point at 229 nm, as shown in Fig. 2. The spectra show also isoabsorptive point at 254 nm which was not involved in the method due to the low sensitivity of the drugs at this wavelength. The absorbance values were measured at 245 nm (λmax for RDV) and 229 nm (λiso) in the range of 1-15 µg/ml and 1-10 µg/ml for RDV and MFX, respectively. Absorptivity values were determined for both RDV and MFX. The values and the absorbance ratio were used to calculate the concentration of RDV and MFX in their binary mixture using Eqs. (3) and (4), respectively.### Bivariate method
To resolve RDV and MFX in their mixture using the bivariate approach, the absorbance of each component separately was measured at seven distinct wavelengths in the overlap region: 245, 255, 265, 275, 285, 295, and 305 nm. To make sure that there was a linear relationship b
Development and Validation of a Spectrophotometric Method for Simultaneous Determination of Remdesivir and Moxifloxacin in Pharmaceutical Preparations
Table of Contents
abstract
A simple, rapid, and accurate spectrophotometric method was developed and validated for the simultaneous determination of remdesivir (RDV) and moxifloxacin (MFX) in their pharmaceutical preparations. The method is based on the formation of ratio spectra using the difference in their UV absorption maxima. The overall ratio spectra were obtained by dividing the spectrum of the mixture with the spectrum of either RDV or MFX at different concentrations. the first derivative of the ratio spectra was used to eliminate the interference effects. The method was validated according to ICH guidelines and showed good linearity (R² > 0.99), accuracy (recovery between 98.5% and 101.5%),precision (RSD < 2%),and specificity.The limits of detection (LOD) and quantification (LOQ) were also determined. The developed method was successfully applied for the determination of RDV and MFX in their combined dosage forms. Introduction
Remdesivir (RDV) is an antiviral medication that has been used to treat COVID-19. Moxifloxacin (MFX) is a broad-spectrum antibiotic used to treat various bacterial infections. The co-administration of these drugs may be necessary in certain clinical situations, necessitating a reliable method for their simultaneous determination. This study describes the development and validation of a spectrophotometric method for the simultaneous determination of RDV and MFX in pharmaceutical preparations.
Materials and Methods
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Results and Discussion
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Ratio Spectra Studies
Ratio spectra were constructed by dividing the absorption spectrum of the mixture containing RDV and MFX by the absorption spectrum of either RDV or MFX at varying concentrations. Figure 4 shows the ratio spectra of RDV (1-10 µg/ml) using 8 µg/ml of MFX as a divisor. Figure 5 illustrates the first derivative of the ratio spectra of RDV, 8 µg/mL, and MFX, 6 µg/mL, using 6 µg/mL of MFX as a divisor. Figure 6 depicts the first derivative of the ratio spectra of MFX, 8 µg/mL, and RDV, 8 µg/mL, using 8 µg/mL of RDV as a divisor. The first derivative technique was employed to enhance the resolution of the spectral bands and eliminate interference effects.
(Figure 4)
(Figure 5)
(Figure 6)
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Conclusion
The developed spectrophotometric method provides a simple, rapid, accurate, and cost-effective approach for the simultaneous determination of RDV and MFX in their pharmaceutical formulations.The method is validated according to ICH guidelines and can be used for routine quality control analysis.
Optimization of experimental conditions
When using ratio-based techniques, it was crucial to carefully select the divisor concentration.Various drug concentrations were tested as divisors; the best ones were 6 µg/ml and 8 µg/ml for RDV and MFX, as they produced the least amount of noise and produced better results in terms of selectivity.
Method validation
The suggested techniques were successfully validated and produced satisfactory results in accordance with ICH criteria [61].
Linearity and range
The response of each drug for each method was plotted against the drug concentrations in µg/ml to create the calibration graphs for each drug for the three methods under the experimental circumstances indicated. The amplitudes of the first derivative of the ratio spectra at 250 nm and 290 nm for RDV and MFX, respectively, are the response for the ratio derivative method. The difference in peak amplitudes between the two chosen wavelengths (247-262) nm and (299-313) nm in the ratio spectra for RDV and MFX,respectively,is
Method evaluation of greenness profiles
The analytical community’s foremost aim is to design procedures that address GC problems. GAC aims to promote a sustainable and eco-amiable approach to analytical chemistry, reducing the environmental effect while maintaining high accuracy and dependability. In recent years, various ways to evaluate greenness have emerged, including qualitative, semi quantitative, and quantitative methods. These approaches were created in line with the 12 GAC principles.The provided approach’s environmental friendliness was assessed using the AGREE, ESA, and ComplexGAPI evaluation techniques. It’s captivating to note that every technique used to gauge greenness supported the idea that it is indeed a very environmentally beneficial approach [65,66,67].
Assessment of greenness in compliance with ESA
A newly developed, comprehensive, semi quantitative instrument for evaluating the greenness of the approach [50]. It relies on deducting points-also known as penalty points-for analytical process characteristics that don’t match the 12 GAC ideas. An analysis that is more environmentally friendly has a higher score (closer to 100). Table 8 displays the ESA scores for the recommended approaches. with a high ESA score of 91 points, the recommended approach’s greenness was instantly apparent.
Assessment of greenness in compliance with complex GAPI
While ESA permits a basic assessment of greenness, Complex GAPI permits a more thorough semi-quantitative analysis [51]. Because it incorporates a hexagon-shaped region that depicts pre-analysis periods and stages, it is superior to the original GAPI measure. From sample collection and transportation to sample safety, storage, preparation, and analysis, this sophisticated tool manages every stage of the analytical process [51]. Simple pictogram software is provided by Complex GAPI. as demonstrated in Table 8, the suggested approach is more environmentally friendly because it demonstrated a lower E-factor (equal to 1), which suggests that the less waste produced, the greater and the more favorable the environmental impact.
Notwithstanding its advantages, ComplexGAPI’s focus is restricted to environmental standards, ignoring energy efficiency, waste reduction, and the integration of renewable resources. If ComplexGAPI is used excessively,it could lead to a limited and insufficient evaluation. This restriction can be addressed and a more thorough review can be obtained by combining ComplexGAPI analysis with quantitative evaluation techniques. in this integrated approach, ComplexGAPI and other supplementary tools will fill in research gaps and solve the limitations of utilizing a single evaluation method.
Assessment of greenness in compliance with AGREE
the most popular greenness assessment metric is AGREE [68]. All 12 of the GAC’s principle
Sustainable Analytical Chemistry: evaluating greenness, Blueness, and Whiteness of Analytical Techniques
Analytical chemistry plays a crucial role in various fields, from pharmaceutical analysis to environmental monitoring. Though, customary analytical methods can frequently enough involve hazardous chemicals, generate significant waste, and be resource-intensive. A growing emphasis on sustainability has led to the development of “green” analytical chemistry principles, aiming to minimize environmental impact while maintaining analytical performance. Recent research highlights the importance of a multi-tool evaluation approach to comprehensively assess the sustainability of analytical techniques, considering not only environmental impact (“greenness”) but also practicality and cost-effectiveness (“blueness”) and overall sustainability including performance and safety (“whiteness”).
The Need for Holistic Sustainability Assessment
Traditionally, evaluating analytical methods focused primarily on accuracy, precision, and sensitivity. However, a truly sustainable approach requires a broader viewpoint. Simply reducing the use of one hazardous chemical isn’t enough; a holistic assessment must consider the entire lifecycle of the analytical process. This includes reagent production, sample preparation, analysis, and waste disposal.
The concept of green analytical chemistry,first formally outlined in 1999 by Anastassiadis et al.[1], emphasizes the design of chemical processes and products that reduce or eliminate the use and generation of hazardous substances. This has evolved to encompass not just environmental considerations, but also economic and social factors.
Defining Greenness, Blueness, and Whiteness
Researchers are increasingly utilizing a range of tools to evaluate analytical methods across these three key dimensions:
Greenness: This refers to the environmental impact of the analytical method. Key considerations include the toxicity of reagents, waste generation, energy consumption, and the use of renewable resources.
Blueness: This focuses on the practicality and cost-effectiveness of the method. Factors like reagent cost, instrument availability, ease of operation, and analysis time are crucial.
Whiteness: This represents the overall sustainability, integrating both greenness and blueness with analytical performance (accuracy, precision, sensitivity) and safety considerations. It provides a comprehensive picture of the method’s sustainability profile.
Tools for Multi-Tool Evaluation
several tools have been developed to quantitatively and qualitatively assess these parameters. Recent studies demonstrate the benefits of combining multiple tools for a more robust evaluation. These include:
ComplexGAPI (Green Analytical Procedure Index): A metric that assesses the environmental impact of analytical procedures based on factors like reagent toxicity,waste generation,and energy consumption. [2]
AGREE (Analytical GREEnness): A tool that evaluates the environmental friendliness of analytical methods, considering aspects like reagent hazards and waste disposal. [3]
ESA (Environmental Significance Assessment): focuses on the environmental impact of analytical processes, providing a quantitative assessment of their sustainability.
BAGI (Biomass, Atom Economy, Greenness, and Impact): Evaluates the sustainability of a chemical process based on biomass usage, atom economy, greenness, and overall environmental impact. RGB12: A framework that assesses analytical methods based on 12 principles of green chemistry, providing a comprehensive sustainability evaluation. [4]
Recent Research & Validation of Sustainable Approaches
A 2024 study published in Microchemical Journal [5] demonstrated the advantages of using these combined tools to evaluate analytical techniques for determining the antiandrogen drug Flutamide in pharmaceutical and environmental samples.The research showcased that the developed analytical techniques exhibited superior sustainability based on criteria such as reduced toxicity, waste minimization, material efficiency, high throughput, automation potential, low cost, and excellent analytical performance.
Further research in 2025 [6] focused on integrating bio-based luminescent carbon quantum dots (CQDs) nanosensors with optimized liquid-liquid microextraction for the sensitive determination of neurological drugs. This approach was also validated as a highly sustainable and implementable best practice,aligning with the environmental,economic,and performance domains of green analytical chemistry. These studies highlight the potential of innovative analytical techniques to minimize environmental impact while maintaining high analytical quality.
key Takeaways
A holistic approach to evaluating analytical methods is crucial for achieving true sustainability.
the concepts of “greenness,” “blueness,” and “whiteness” provide a framework for assessing sustainability across environmental,economic,and performance dimensions.
Combining multiple evaluation tools (ComplexGAPI, AGREE, ESA, BAGI, RGB12) provides a more robust and comprehensive assessment.
Recent research demonstrates the feasibility of developing highly sustainable analytical techniques that minimize environmental impact while maintaining high performance.
Future Directions
The field of sustainable analytical chemistry is continuously evolving. Future research will likely focus on developing even more environmentally friendly reagents and solvents,miniaturizing analytical instruments to reduce energy consumption,and implementing automated systems to improve efficiency and reduce waste. The integration of artificial intelligence and machine learning could also play a role in optimizing analytical methods for sustainability. Ultimately, the goal is to create analytical processes that