Development and Validation of Spectrophotometric and Turbidimetric Methods for the Sensitive Determination of Cefixime Trihydrate in Pure and Commercial Dosage Forms

This study introduces two innovative analytical methods for the sensitive determination of cefixime trihydrate (CEF) in pure and commercial dosage forms: a spectrophotometric method utilizing a chromogenic reaction with Coomassie brilliant blue and a turbidimetric approach based on colloidal complexation with sodium phosphotungstate. The spectrophotometric method relies on the formation of a red chelate complex (λmax = 517 nm) under optimized alkaline conditions (0.05 M NaOH), demonstrating a linear range of 40–400 µg/mL, with limits of detection (LOD) and quantification (LOQ) of 0.91 and 2.77 µg/mL, respectively. The turbidimetric method quantifies CEF via light scattering (600 nm) of colloidal aggregates, achieving a linear range of 3–55 µg/mL, an LOD of 4.80 µg/mL, and an LOQ of 14.45 µg/mL. Both methods were rigorously validated according to International Council for Harmonisation/U.S. Food and Drug Administration guidelines, exhibiting excellent precision (relative standard deviation < 2%), accuracy (recoveries: 96.5–99.8% for spectrophotometry; 85.5–96.6% for turbidimetry), and specificity against excipients and degradation products. Statistical validation (t-test, F-test) confirmed equivalence to high-performance liquid chromatography (p > 0.05). The spectrophotometric method offers superior sensitivity and precision, while the turbidimetric approach provides rapid, cost-effective analysis. These validated methods serve as robust alternatives to chromatographic techniques, enhancing accessibility for pharmaceutical quality control in diverse settings.