Normal and reverse flow injection- spectrophotometric determination of doxycycline hyclate in bulk and pharmaceutical samples

The present paper reports the development and validation of an analytical method for doxycycline hyclate (DOX) quantification in pure and dosage forms by normal and reverse flow injection analysis (FIA) techniques. Two types of FIA approaches were employed to automate a diazotization coupling reaction of DOX with diazotized benzidine dihydrochloride. Red azo dye was formed rapidly and measured at maximum wavelength of 488 nm. Calibration curves were prepared over different DOX concentrations with linearity ranges of 10-250 and 1-180 µg/mL for normal and reverse FIA systems respectively with the limits of detection of 2.95 and 0.46 µg/mL and limits of quantitation of 9.83 and 1.55 µg/mL, respectively. The developed approaches were then used to determine DOX in pharmaceutical dosage forms with high percentage recoveries and low %RSD. In concordance with the standard method, the proposed techniques demonstrated rapid detection and applicability in pharmaceutical analysis.