A Novel method of CFIA/Merging zones technique for assay of Doxycycline in bulk and pharmaceutical preparation depending on Azo dye formation

A simple, automated and sensitive flow-injection analysis/merging zones technique (MZ-FIA) method was developed for the determination of doxycycline hyclate (DOX) in pure and pharmaceutical formulations. This method Involved the reaction of AzoAnthranilic Acid with DOX to produce an orange-yellowish dissolved complex which has maximum absorbance at 468nm. The method was sensitive, precise and accurate were the limit of detection was less than (0.3μg/ml) and the RSD% was less than 1% and Recovery was 98–100%. Various chemical and physical conditions that affected the reaction have been studied. The calibration curve was rectilinear within the concentration range 5–125μg/mL with a sample through put of 80 sample/hour. The proposed procedure was applied successfully for the estimation of DOX and the results obtained were favorably compared with those given by a reference method of British Pharmacopeia, and there was no significant difference between the obtained results, regarding accuracy and precision at the 95% confidence level.