Green Chemistry-Based Development and Validation of a UV-Spectrophotometric Method for the Estimation of Metformin Hydrochloride in Bulk and Tablet Dosage Form

Metformin hydrochloride (HCl) is chemically a (N, N-dimethyl imidodicarbonimidic diamide monohydrochloride. When treating diabetes mellitus type II, metformin HCl is utilized. It reduces plasma free fatty acid concentrations, increases glucose transport into cells, inhibits gluconeogenesis, and decreases glucose absorption in the small intestine. AMPK activation is essential to these processes^{. (1)} A review of the literature found that there were relatively few studies on analytical techniques for Metformin, including UV-Visible, HPLC, LC-MS, LC-MS/MS, and HPTLC for the determination of Metformin HCl from the bulk and dosage form. The reported methods' solvent use was not very cost-effective. ^(6-11) Green chemistry is the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances^{. (4)} Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, use, and ultimate disposal. ⁽²⁾ Green chemistry covers all aspects of a chemical product's life cycle, including its creation, use, and final disposal. In order to analyse analytical techniques' environmental impact and demonstrate their viability in developing sustainable strategies, the evaluation of their "greenness" is becoming more and more important. Some Tolls are used to measured Analytical Eco-Scale, HPLC-Environmental Assessment Tool (HPLC-EAT), Analytical Method Volume Intensity (AMVI), Green Analytical Procedure Index (GAPI), Analytical Method Greenness Score (AMGS) Calculator, National Environmental Method Index (NEMI), Assessment of Green Profile established by Raynie & Driver, and other tools are some examples of green metrics approaches that have been researched. Concerns have been expressed regarding the necessity of implementing such metric tools in method development rather than post analysis evaluation, as well as the potential of understanding how to use such assessment tools to minimise the hazardous environmental effect of harmful chemicals and regulate irresponsible activities. By Using Green Chemistry Which Results in source reduction because it prevents the generation of pollution, Reduces the negative impacts of chemical products and processes on human health and the environment, Lessens and sometimes eliminates hazard from existing products and processes, designs chemical products and processes to reduce their intrinsic hazards. ^(12-13)

MATERIALS AND METHODS

Instrument

A Shimadzu UV-1800 240V UV/VISIBLE spectrophotometer was used having two matched 1 cm matches quartz cell

Table 1 List of Instrument and Apparatus

Chemical and reagents

All the reagents and solvents were of analytical grade high purity. Metformin HCl was purchased from Globela Health Care Limited, Surat, India. All other chemicals used were of analytical grade.

Preparation of Standard Stock Solutions

100 mg of Metformin HCL was weighed separately and transferred in 100 mL volumetric flasks. The drugs were dissolved in 50 mL of distilled water by sonication and then the volume was made up to the mark with the same solvent to obtain final concentration 1000 µg/ml of the component.

Preparation of Sample Solution

Powder of twenty tablets (Marketed tablets of metformin; Glycomet-500 S.R.), containing 500 mg Metformin HCl, was weighed. A quantity of powder equivalent to 10 mg of Metformin HCl was taken in different 10 mL volumetric flasks containing about 5 mL distilled water for analysis and sonicated for 15 min. After sonication, the volume was made up to the mark with the same solution to obtain sample stock solution of Metformin HCl (1000 µg/mL).

Preparation of Working Standard Solution

Suitable aliquots of 1000 mg/ml solution were diluted up to the mark with water to get the concentration range of 2, 4, 6, 8 and 10 mg mL-1 for Metformin HCL. The absorbance was measured at 234 nm.

Selection of wavelength

The wavelength for the analysis of Metformin HCl (6 µg/mL) was selected from the UV spectrum. The standard solution of Metformin HCl was scanned in the range of 200-400 nm and the λmax was found to be 234 nm against water.

Method validation

The developed UV-spectrophotometric method for the estimation of Metformin Hydrochloride was validated as per ICH Q2(R1) guidelines for the following parameters.

Linearity

Linearity was assessed over the concentration range of 5–10 µg/mL. A calibration curve was constructed by plotting absorbance against concentration. The method showed good linearity with a correlation coefficient (R²) of > 0.999, indicating a strong linear relationship.

Accuracy

Accuracy was determined by recovery studies using the standard addition method at three levels (80%, 100%, and 120%). The % recovery was found in the range of 98% to 102%, confirming the accuracy of the method

Precision

Repeatability (Intra-day precision): Evaluated by analyzing three concentrations (4, 6, and 8 µg/mL) three times within a single day.

Intermediate precision (Inter-day precision): Assessed by repeating the same procedure on three consecutive days. The %RSD for both intra- and inter-day precision was found to be < 2%, indicating good precision.

Specificity

The method showed no interference from tablet excipients. The blank solution showed negligible absorbance at 234 nm, confirming the specificity of the method for Metformin Hydrochloride.

LOD and LOQ

LOD (Limit of Detection) and LOQ (Limit of Quantitation) values in your article, assuming you're following standard UV-spectrophotometric calculation methods using the formula:

LOD = 3.3 × (σ / S)

LOQ = 10 × (σ / S)

Where:

σ = Standard deviation of the response

S = Slope of the calibration curve

The LOD and LOQ were found to be 0.34 µg/mL and 1.02 µg/mL, respectively

Robustness

Robustness was tested by making small deliberate variations in parameters such as wavelength (±1 nm) and Change Analyst (1 and 2)). These changes did not significantly affect the absorbance, confirming the robustness of the method.

RESULT AND DISCUSSION

To optimize the UV parameters, several conditions were tried to achieve a good absorption and peak shape for Metformin HCl. Several solvents of different compositions were tried to provide sufficient selectivity towards the drugs. Distilled water components resulted in better sensitivity. The methods discussed in the present work provide a convenient and accurate way for the analysis of Metformin HCl from bulk and tablet dosage form by UV Spectro- photometry method. The 234 nm wavelength was selected for analysis of Metformin HCl Figure 1. The absorbance of Metformin HCl was found to be 0.385. Selected methods linearity was observed in the concentration range of 2-10 µg/mL.  A Linear correlation was obtained between absorbance Vs concentration. Calibration curve for Metformin HCl showed linearity in the concentration range 2-10 µg/mL. The linearity of the calibration curve was validated by the value of correlation coefficients (R²). The value of correlation coefficient for Metformin HCl was found to be 0.999 shown in Figure 2. The standard addition method was employed for accuracy measurement. The percentage recoveries for Metformin HCl were found in the range of 98.2.6 to 101.58 %. The values of the recovery (%) and %RSD were shown Table 3. The precision of the method was determined by analysing the drug formulation by replicate injections and precision of the system was determined by mixed standard solutions. % RSD of the analyte was found to be within the limit of % RSD were Shown in Table 4. Robustness was determined by performing the assay with the same condition on different days, by different analysts, different instrument and different time. The values of the Robustness shown in Table 5.

Figure 1: UV Spectrum of Metformin

Table 2 Calibration curve of Metformin at 234 nm

Figure 2 Calibration curve of Metformin Hydrochloride (2 to 10 µg/ml)

Table 3: Recovery of Metformin Hydrochloride

Table 4: Precision for Metformin Hydrochloride at 234nm

Table 5: Robustness

Figure 4 Green Chemistry GAPI

Table: - Score Card for Green Chemistry