title: Study of 1,4-naphthoquinone as a new useful derivatization reagent for LC analysis of aliphatic thiols in dietary supplements and pharmaceuticals.
abstract: The use of 1,4-naphthoquinone as an advantageous pre-column reagent for liquid chromatography analysis of aliphatic thiol compounds is proposed. The compound reacts selectively in mild conditions (5 min at room temperature; pH 7.5) with thiol function. The resulting adducts were separated under isocratic conditions by using a reversed-phase column (C-12n) with a mobile phase corresponding to methanol/triethylammonium phosphate buffer (pH 3; 0.05 mol L(-1)) 65:35, v/v, at a flow rate of 0.4 mL min(-1) in presence of quercetin as internal standard. Detection was set at a wavelength of 420 nm. The effect of the derivatization reaction conditions on the N-acetylcysteine (NAC) reaction yield was investigated by a series of experiments. The yield of NAC derivative was found to be quantitative at a reagent thiol molar ratio of about 3 by comparison with an authentic specimen of synthesized NAC adduct, which was characterized by (1) H NMR, IR, and UV. Similar linear responses were observed by standard and placebo solutions (determination coefficient, 0.9998). The within- and between-day standard deviations (RSD) were ≤0.47 %. Recovery studies showed good results (100.03 %) with RSD 0.76 %. The limit of detection was about 20 pmol. The utility of the validated method for the determination of NAC in a new dietary supplement and commercial formulations is demonstrated.
authors: Department of Pharmaceutical Science, Alma Mater Studiorum-University of Bologna, Bologna, Italy. rita.gatti2@unibo.it
authors: Rita
authors: R
authors: Gatti
authors: Paolo
authors: P
authors: Andreatta
authors: Silvia
authors: S
authors: Boschetti
mesh_terms: D000111:Acetylcysteine / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods*; D019587:Dietary Supplements / Q000032:analysis*; D009285:Naphthoquinones / Q000737:chemistry*; D004364:Pharmaceutical Preparations / Q000032:analysis*; D013438:Sulfhydryl Compounds / Q000032:analysis*
chemical_list: D009285:Naphthoquinones; D004364:Pharmaceutical Preparations; D013438:Sulfhydryl Compounds; C035342:1,4-naphthoquinone; D000111:Acetylcysteine