Applicability of ninhydrin as a fluorescent reagent for estimation of teicoplanin in human plasma using salting-out assisted liquid-liquid extraction technique

The applicability of ninhydrin, a widely used derivatizing reagent, for determination of teicoplanin (TEIC) in its pure form, pharmaceutical vials, and in human plasma was investigated. The presented spectrofluorimetric method was based on a condensation reaction between ninhydrin and the primary amine group existing in TEIC (in the presence of phenylacetaldehyde) to produce a highly fluorescent product detected at 460 nm (lambda(ex),390 nm). Calibration plots were constructed in the concentration range 60-600 ng mL(-1) with a good correlation coefficient of 0.9998 and a low detection limit of 10.84 ng mL(-1). The method was subjected to a bioanalytical validation study according to US-FDA recommendations. The proposed method was applied for analysis of TEIC in commercial vials with high recovery result 101.88 +/- 1.11%. In addition, the method was utilized efficiently for detection of TEIC in human plasma using salting-out assisted liquid-liquid extraction technique (SALLE) with a recovery range from 96.71 +/- 1.08% to 97.71 +/- 0.86%. SALLE is an effective approach used for extraction of TEIC from human plasma without interferences using ammonium sulphate. The proposed method is highly recommended to monitor TEIC in clinical laboratory samples and therapeutic drug monitoring systems.