Chemiluminescence determination of surfactant Triton X-100 in environmental water with luminol-hydrogen peroxide system

<p>Abstract</p> <p>Background</p> <p>The rapid, simple determination of surfactants in environmental samples is essential because of the extensive use and its potential as contaminants. We describe a simple, rapid chemiluminescence method for the direct determination of the non-ionic surfactant Triton X-100 (polyethylene glycol tert-octylphenyl ether) in environmental water samples. The optimized experimental conditions were selected, and the mechanism of the Luminol-H₂O₂-Triton X-100 chemiluminesence system was also studied.</p> <p>Results</p> <p>The novel chemiluminescence method for the determination of non-ionic surfactant Triton X-100 was based on the phenomenon that Triton X-100 greatly enhanced the CL signal of the luminol-H₂O₂system. The alkaline medium of luminol and the pH value obviously affected the results. Luminol concentration and hydrogen peroxide concentration also affected the results. The optimal conditions were: Na₂CO₃being the medium, pH value 12.5, luminol concentration 1.0 × 10^-4mol L^-1, H₂O₂concentration 0.4 mol L^-1. The possible mechanism was studied and proposed.</p> <p>Conclusion</p> <p>Under the optimal conditions, the standard curve was drawn up and quotas were evaluated. The linear range was 2 × 10^-4g·mL^-1-4 × 10^-2g·mL^-1(w/v), and the detection limit was 3.97 × 10^-5g·mL^-1Triton X-100 (w/v). The relative standard deviation was less than 4.73% for 2 × 10^-2g·mL^-1(w/v) Triton X-100 (n = 7). This method has been applied to the determination of Triton X-100 in environmental water samples. The desirable recovery ratio was between 96%–102% and the relative standard deviation was 2.5%–3.3%. The luminescence mechanism was also discussed in detail based on the fluorescence spectrum and the kinetic curve, and demonstrated that Triton X-100-luminol-H₂O₂was a rapid reaction.</p

Dynamic Pricing in the Presence of Strategic Consumers with "Experience-in-Store-and-Buy-Online"

National Natural Science Foundation of China under Grants 72071074 and 71671061; Outstanding Young Foundation of Hunan Province Natural Science under Grants 2018JJ1003

Heuristic Approaches for the Robust Vehicle Routing Problem

11 páginasIn this article, the Robust Vehicle Routing Problem (RVRP) with uncertain traveling costs is studied. It covers a number of important applications in urban transportation and large scale bio-terrorism emergency. The uncertain data are defined as a bounded set of discrete scenarios associated with each arc of the transportation network. The objective is to determine a set of vehicle routes minimizing the worst total cost over all scenarios. A mixed integer linear program is proposed to model the problem. Then, we adapt some classical VRP heuristics to the RVRP, such as Clarke and Wright, randomized Clarke and Wright, Sequential Best Insertion, Parallel Best Insertion and the Pilot versions of the Best Insertion heuristics. In addition, a local search is developed to improve the obtained solutions and be integrated in a Greedy Randomized Adaptive Search Procedure (GRASP). Computational results are presented for both the mathematical formulation and the proposed heuristics