Flow injection chemiluminescence determination of ethion and computational investigation of the adsorption process on molecularly imprinted polymerized high internal phase emulsion.

The lack of sufficient selectivity is the main limitation of chemiluminescence (CL) methods; because the CL reagent is not restricted to a specific analyte. This study investigated the preconcentration and determination of ethion using a flow injection CL (FIA-CL) method using a molecularly imprinted poly high internal phase emulsion (MIP-polyHIPE) adsorbent. Preliminary studies showed that ethion could be determined with high sensitivity in the Ru(bipy)3 2+ -acidic Ce(IV) CL system. A MIP-polyHIPE adsorbent was synthesized and used for preconcentration to increase the selectivity and sensitivity of the method. The adsorption of ethion on the adsorbent was investigated using density functional theory (DFT) and molecular dynamics (MD), UV-vis and FTIR spectrophotometry and liquid chromatography-tandem mass spectrometry (LC-MS-MS). Response surface methodology (RSM) and central composite design (CCD) were used to find optimized concentrations of variables. The linear dynamic range (LDR) and limit of detection (LOD) for ethion in the FIA-CL method were calculated 1.0 ⨯ 10-9 to 2.0 ⨯ 10-7 and 6.0 ⨯ 10-10  mol L-1 , respectively. The percentage of relative standard deviation for five repetitive measurements of 5.0 ⨯ 10-8  mol L-1 ethion was 4.2%. The proposed method was successfully used to separate and preconcentrate ethion from drinking and surface water sources.

Pulsed-sonochemiluminescence combined with molecularly imprinted polymerized high internal phase emulsion adsorbent for determination of bentazone.

A small low-power humidifier with a simple programmable on/off switch was used as a pulsed ultrasound generator. Using this tool, a novel sonochemiluminescence (SCL) method was developed to determine bentazone. To the best of our knowledge, no chemiluminescence method has been proposed to determine this pesticide. Only five studies have been proposed for SCL quantitative applications so far. Therefore, revealing new aspects of SCL promises to develop analytical methods for the quantitative determination of different substances. A molecularly imprinted polymerized high internal phase emulsion (MIP-polyHIPE) was synthesized, bentazone separated from aqueous solutions, and pre-concentrated by the MIP-polyHIPE foam. The adsorption of bentazone on the MIP-polyHIPE adsorbent was theoretically studied by density functional theory through molecular dynamics simulation. Both experimental and simulation results indicated removal and pre-concentration of bentazone by the MIP-polyHIPE adsorbent. Using the proposed SCL method and without pre-concentration process, a linear dynamic range (LDR) of 2.5 × 10-7-5.0 × 10-5 mol L-1 and a limit of detection (LOD) of 8.4 × 10-8 mol L-1 were obtained for bentazone with a relative standard deviation of 2.64%. The LDR and LOD were improved to 2.6 × 10-9-2.0 × 10-7 mol L-1 and 8.8 × 10-10 mol L-1, respectively, using MIP-polyHIPE adsorbents. The method's application was evaluated by removing and pre-concentration of bentazone from water samples, including well, river, and tap water. The results showed that the pre-concentration factor and recovery percentages were 113-131 times and 93-106%, respectively, using the MIP-polyHIPE absorbent.

Stopped-flow chemiluminescence determination of the anticancer drug capecitabine: Application in pharmaceutical analysis and drug-delivery systems.

Capecitabine is a chemotherapeutic agent used for the treatment of patients with metastatic cancers. This study aimed at determining the drug capecitabine in a simple chemiluminescence (CL) system of acidic potassium permanganate using the stopped-flow injection technique. Statistical methods were used to detect optimum conditions. The method showed two linear calibration ranges from 6.7 × 10-6 to 6.7 × 10-5 mol L-1 and from 6.7 × 10-5 to 2.7 × 10-3 mol L-1 with a detection limit of 1.5 × 10-6 mol L-1 . Chitosan-modified magnetic nanoparticles were studied in the drug-delivery experiments. According to the pH sensitivity of chitosan and low pH values in tumour cells, the chitosan-coated magnetic nanoparticles could provide a good targeting drug-delivery system to tumour sites. To evaluate the applicability of the method, the capecitabine-loaded magnetic chitosan nanoparticles were synthesized with two different cross-linkers; loading and releasing rates of the drug were investigated using the proposed CL method and an ultraviolet-visible light spectrophotometric method (absorption at 305 nm). The results showed a good correlation between the two methods, and it was found that the synthesized chitosan-modified magnetic nanoparticles could be used for pH-dependent release of capecitabine in cancer cells. Moreover, determination of capecitabine in tablets and synthetic samples was performed.

Well-distributed 1T/2H MoS2 nanocrystals in the N-doped nanoporous carbon framework by direct pyrolysis.

Molybdenum disulfide (MoS2) has been a promising anode material in lithium-ion batteries (LIBs) because of its high theoretical capacity and large interlayer spacing. However, its intrinsic poor electrical conductivity and large volume changes during the lithiation/delithiation reactions limit its practical application. An efficient synthesis strategy was developed to prepare the MoS2 nanocrystals well-anchored into the N-doped nanoporous carbon framework to deal with these challenges by a confined reaction space in an acrylonitrile-based porous polymer during the carbonization process. The prepared hybrid material comprises small 1T/2H-MoS2 nanoparticles surrounded by a nanoporous carbon matrix. In addition to the highly crystalline nature of the synthesized MoS2, the low ID/IG of the Raman spectrum demonstrated the development of graphitic domains in the carbon support during low-temperature pyrolysis (700 °C). This novel three-dimensional (3D) hierarchical composite shows superior advantages, such as decreased diffusion lengths of lithium ions, preventing the agglomeration of MoS2 nanocrystals, and maintaining the whole structural stability. The prepared C/MoS2 hybrid demonstrated fast rate performance and satisfactory cycling stability as an anode material for LIBs.

A molecularly imprinted polymerized high internal phase emulsion adsorbent for sensitive chemiluminescence determination of clopidogrel.

A molecularly imprinted polymerized high internal phase emulsion (MIP-polyHIPE) adsorbent was used for selective separating and preconcentrating the anti-plaque drug, clopidogrel. For the first time in this study, chemiluminescence (CL) methods were evaluated for the determination of clopidogrel. The synthesis of adsorbents by the emulsion templating method showed that the sensitivity of the method can be increased up to 42 times. The determination of clopidogrel was evaluated by Ru(phen)32+-Cerium (IV), KMnO4-H2SO4, KMnO4-H2SO4-Na2SO3, and luminol-H2O2 CL systems. According to the results, only the Ru(phen)32+-Cerium (IV) CL system showed a reasonable sensitivity for clopidogrel. Using MIP-polyHIPE adsorbent, the linear range, the limit of detection, and relative standard deviation for clopidogrel in this system were respectively 1.0 × 10-9-8.0 × 10-8 mol L-1, 3.0 × 10-10 mol L-1, and 6.3% (n = 4, 1.0 × 10-8). The proposed method was employed for determining clopidogrel in pharmaceuticals and blood serum samples. The results showed the good sensitivity and accuracy of the proposed method.