Validated Spectrophotometric Determination of Meloxicam via Azo-Coupling Reactions with Barbituric Acid and 8-Hydroxyquinoline

Two sensitive, simple, accurate, and rapid spectrophotometric methods have been developed for the estimation of Meloxicam in bulk drug and tablet dosage forms. Method A involves the reaction of Meloxicam with barbituric acid in a basic medium, followed by the addition of sodium nitrite to produce the corresponding primary aromatic amine, while Method B involves the azo-coupling reaction of Meloxicam with 8-hydroxyquinoline in the presence of sodium nitrite in a basic medium. Both methods exhibited excellent linear absorption–concentration dependencies, with correlation coefficients of 0.9998 and 0.9995 for the Method A and the Method B over the concentration ranges of 5.0–25.0 μg/mL and 5.0–35.0 μg/mL, respectively. Additionally, the molar absorptivity and Sandell sensitivity values were 0.94166·104 L/(mol·cm) and 6.37·10–3 μg/cm² for the Method A, and 1.326·104 L/(mol·cm) and 5.653·10–3 μg/cm² for the Method B, respectively. The Method A demonstrated the recovery within the range of 99.33–101.00 %, while the Method B gave the results within the range of 99.25–101.00 %, with an LOQ of 0.250 μg/mL and 0.503 μg/mL, respectively. These two methods demonstrated the ability to estimate Meloxicam in the pharmaceutical dosage form without interference from tablet additives, with an excellent agreement with the standard method. These characteristics make the proposed methods appropriate for the quality control of Meloxicam in bulk drug and tablet dosage forms.