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Li L.,Northwest Normal University | Li L.,Key Laboratory of Bioelectrochemtry Environmental Analysis of Gansu | Li L.,Lanzhou University | Guo R.,Northwest Normal University | And 5 more authors.
Luminescence | Year: 2015

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. © 2014 John Wiley & Sons, Ltd.

Wang X.,Northwest Normal University | Wang X.,Key Laboratory of Bioelectrochemtry Environmental Analysis of Gansu | Rao H.,Northwest Normal University | Lu X.,Northwest Normal University | And 3 more authors.
Talanta | Year: 2013

Octyl-functionalizd mesoporous SBA-15 was first used as precursor and selective stationary phase to prepare solid-phase microextraction (SPME) fiber by using the sol-gel technique. The new SPME coating possessed honeycomb-like porous structure and rough surface and showed excellent chemical stability and longer life span (over 200 cycles of usage). The performance of the octyl-SBA-15-coated fiber was tested through extraction of eight polycyclic aromatic hydrocarbons (PAHs). The results showed that the home-made SPME fiber exhibited higher extraction efficiency compared with the commercial SPME (30 μm and 100 μm PDMS) fibers. For PAHs analysis, the new fiber showed good precision (<4.8%), low detection limits (0.024-0.050 μg/L), and wide linearity (0.1-200 μg/L) under the optimized conditions. The repeatability of fiber-to-fiber and batch-to-batch was 3.2-8.4% and 4.4-9.5%, respectively. The method was applied to simultaneous analysis of eight PAHs with satisfactory recoveries in different spiking levels, which were 85.7-103.4% (10 μg/L) and 87.0-107.2% (50 μg/L) for water samples and 76.2-89.0% (10 μg/g) and 75.6%-91.2% (50 μg/g) for soil samples, respectively. © 2012 Elsevier B.V.

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