RP-HPLC assay of doxycycline in human saliva and gingival crevicular fluid in patients with chronic periodontal disease

► RP-HPLC-FLD method for determination of doxycycline was developed and validated. ► Tetracycline was used as internal standard. ► The simple extraction with ACN without the sample concentration was described. ► The proposed method was successfully applied to the analysis of DOXY in human saliva and GCF. ► Low values for LODs and LOQs allowed precise identification and quantification.