title: A novel system of galangin-potassium permanganate-polyphosphoric acid for the determination of tryptophan and its chemiluminescence mechanism.
abstract: A novel galangin-potassium permanganate (KMnO4)-polyphosphoric acid (PPA) system was found to have an outstanding response to tryptophan (Trp). Trp determination using this KMnO4 -PPA system was enhanced significantly in the presence of galangin. A highly sensitive flow-injection chemiluminescence (CL) method to determine Trp was developed based on the CL reaction of galangin-KMnO4 -Trp in PPA media. The presence of galangin, a member of the flavonol class of flavonoid complexes, greatly increased the luminous intensity of Trp in KMnO4 -PPA systems. Under optimized conditions, Trp was determined in the 0.05-10 µg/mL range, with a detection limit (3σ) of 5.0 × 10(-3)  µg/mL. The relative standard deviation (RSD) was 1.0% for 11 replicate determinations of 1.0 µg/mL Trp. Two synthetic samples were determined selectively with recoveries of 98.4-100.1% in the presence of other amino acids. The possible mechanism is summarized as follows: excited states of Mn(II)(*) and Mn(III(*) types are the main means of generating chemical luminescent species, and Trp concentration and luminescence intensity have a linear relationship, which enables quantitative analysis.
authors.affiliation: College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, China.|Key Lab of Bioelectrochemtry Environmental Analysis of Gansu, Lanzhou, 730070, China.|College of science, Gansu Agriculture University, Lanzhou, 730070, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.affiliation: College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, China.|Key Lab of Bioelectrochemtry Environmental Analysis of Gansu, Lanzhou, 730070, China.
authors.forename: Ruibin
authors.initials: R
authors.lastname: Guo
authors.affiliation: College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, China.|Key Lab of Bioelectrochemtry Environmental Analysis of Gansu, Lanzhou, 730070, China.
authors.forename: Dongxia
authors.initials: D
authors.lastname: Zhang
authors.affiliation: College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou, 730070, China.|Key Lab of Bioelectrochemtry Environmental Analysis of Gansu, Lanzhou, 730070, China.
authors.forename: Xinzhen
authors.initials: X
authors.lastname: Du
mesh_terms: D002138:Calibration; D005419:Flavonoids / Q000737:chemistry*; D049449:Luminescence; D008163:Luminescent Measurements / Q000295:instrumentation / Q000379:methods*; D010084:Oxidation-Reduction; D010756:Phosphoric Acids / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D011196:Potassium Permanganate / Q000737:chemistry*; D014364:Tryptophan / Q000032:analysis* / Q000737:chemistry
chemical_list: D005419:Flavonoids; D010756:Phosphoric Acids; D011108:Polymers; D011196:Potassium Permanganate; C037032:galangin; C047269:polyphosphoric acid; D014364:Tryptophan
keywords: chemiluminescence; galangin; mechanism; potassium permanganate; tryptophan