نظام حقن جرياني وطيفي لتقدير حامض الميفانيميك باستخدام معقدي انتقال الشحنة بين النحاس والكروم مع كاشف النيوكابريون

Flow Injection System and Spectrophotometry for The Determination of Mefenamic Acid Using Charge Transfer Complexes Between Copper and Chromium with Neocuproine Reagent

SUMMARY
The first part involves developing indirect, simple, accurate, fast, selective, and highly sensitive spectrophotometric method using the copper-neocuproine complex for the determination of trace amounts of mefenamic acid in aqueous solutions and pharmaceuticals. The proposed method relies on forming complexes using the redox reaction, where the suggested approach involves reducing the Cu(II)-Neocuproine complex to the yellow-orange Cu(I)-Neocuproine complex. Optimal experimental conditions such as acidity, stability time of the formed complex, buffer solutions, volume and concentration of copper (ІІ), volume and concentration of the reagent (Neocuproine), temperature, sequence of addition, and the impact of interferences on complex estimation were chosen. The calibration curves exhibited linearity in the concentration range of 5.0-60.0 μg.2mL-1, with a molar absorptivity (ɛ) value of 0.238 L. moL-1.cm at 454 nm. The linearity coefficient(R2) was found to be 0.9999, and the equivalence of the complexes was studied by finding the metal ion to reagent ratio (M: L) using the continuous variations and molar ratio methods. The results indicated that this ratio was 1:2. The stability constant (Ksta) for the formed complex was calculated and found to be (3.5×108). The charge of the soluble solid complex in ethanol was determined by measuring the conductivity of the formed complex, revealing that the [Cu(Ι)-Neocuproine] complex is charged. The accuracy and precision of the spectrophotometric method were evaluated using five solutions of different concentrations, resulting in a relative standard deviation percentage between (0.037% to 0.500%) and a recovery percentage between (99.50% to 100.32%). Detection and quantification limits were determined to be 0.7142 μg.mL-1 and 2.3568 μg.mL-1, respectively. These results indicate that the spectrophotometric method is highly sensitive, accurate, and was successfully applied to aqueous and pharmaceutical solutions.
The second part included the design of an advanced flow injection system for the determination of mefenamic acid in pharmaceutical preparations (Ponstidin, Ponstan, Mefril), and aqueous solutions. The proposed method for mefenamic acid determination using continuous flow injection relied on the spectrophotometric reagent reaction neocuproine with copper (II) in the presence of mefenamic acid in an acidic medium to form the copper(I)-neocuproine complex. The absorbance of the formed yellow-orange complex was measured at its maximum wavelength of 454 nm. The optimal chemical and physical conditions for the proposed system were achieved the highest sensitivity, stability, and the best design for optimal response. Calibration curves demonstrated linearity in the concentration range of 1.0-80.0 μg.2mL-1, with a Linearity coefficient (R2) of 0.9998. The accuracy and precision of the method (continuous flow injection) were assessed using five solutions of different concentrations, resulting in a relative standard deviation percentage between (0.0235% to 0.0115%) and a recovery percentage between (99.30% to 99.94%). Detection and quantification limits were found to be (0.1983 μg.mL-1) and (0.6543 μg.mL-1), respectively. The proposed method exhibited good characteristics such as speed, sensitivity, repeatability, and precision, making it suitable for quantitative determination of mefenamic acid in pharmaceutical preparations and aqueous solutions. The proposed method was successfully applied to aqueous and pharmaceutical solutions, demonstrating high sensitivity and accuracy in determination.
The third part involved the development of a fast, direct, sensitive, accurate, and efficient spectrophotometric method for the determination of mefenamic acid in aqueous solutions and pharmaceutical drugs. The method relied on the formation of complexes using the redox reaction, converting the Cr(VI)-2,9DMP complex to the yellow-green Cr(III)-2,9DMP complex at 430nm. The favorable experimental conditions for the reaction were selected, including acidity, stability time of the formed complex, regulated solutions, volume, and concentration of chromium (VI), volume and concentration of the reagent (neocuproine), temperature, and the order of addition. Calibration curves demonstrated linearity in the concentration range of 4.0-70.0 μg.2mL-1, with a linearity coefficient (R2) of 0.9998. The molar ratio of metal ion to the reagent (M: L) was determined using continuous variation method, indicating a ratio of (1:3). The stability constant (Ksta) for the formed complex was calculated and found to be (1.369×1010). The charge of the soluble solid complex in ethanol was determined by measuring the conductivity of the formed complex, indicating that the complex [Cr(III)-Neocuproine] was charged. The accuracy and precision of the spectrophotometric method were evaluated using five solutions of different concentrations, resulting in a relative standard deviation percentage between (0.433% to 0.909%) and a recovery percentage between (99.90% to 101.10%). Detection and quantification limits were found to be (0.6111 μg.mL-1) and (1.8333 μg.mL-1), respectively. The proposed spectrophotometric method demonstrated high sensitivity and accuracy and was successfully applied to aqueous solutions and pharmaceutical preparations.
The fourth part included the design of an advanced flow injection system for the determination of mefenamic acid in pharmaceutical preparations (Ponstidin, Ponstan, Mefril) and aqueous solutions. The proposed method for mefenamic acid determination using continuous flow injection relied on the reaction of the spectrophotometric reagent neocuproine with chromium (VI) in the presence of mefenamic acid in an acidic medium to form the colored chromium (III)-neocuproine complex (yellow-green). The absorbance of the formed colored complex was measured at the maximum wavelength of 430 nm. The favorable chemical and physical conditions for the proposed system were studied to achieve higher sensitivity, stability, and optimal design for the best response. Calibration curves exhibited linearity in the concentration range of 0.1-60.0 μg.2mL-1, with a linearity coefficient (R2) of 0.9998. The precision and accuracy of the continuous flow injection method were evaluated using five solutions of different concentrations, resulting in a relative standard deviation percentage between (0.4838% to 3.2680%) and a recovery percentage between (97.50% to 102.40%). Detection and quantification limits were found to be (0.1424 μg.mL-1) and (0.4274 μg.mL-1), respectively. The proposed method demonstrated good characteristics such as speed, sensitivity, and reliability, and it was successfully applied to aqueous solutions and pharmaceutical preparations, showing high sensitivity and accuracy in the determination process.