Dong Chuan

Study on the paper substrate room temperature phosphorescence of theobromine, caffeine and theophylline and analytical application

Paper substrate room temperature phosphorescence (RTP) of theobromine (TB), caffeine (CF) and theophylline (TP) were investigated. The method is based on fast speed quantitative filter paper as substrate and KI-NaAc as heavy atom perturber. Various factors affecting their RTP were discussed in detail. Under the optimum experimental conditions, the linear dynamic range, limit of detection (LOD), and relative standard deviation (R.S.D.) were 14.41 approximately 576.54 ng per spot, 1.14 ng per spot, 4.8% for TB, 5.44 approximately 699.08 ng per spot, 0.78 ng per spot, 1.56% for CF, 7.21 approximately 360.34 ng per spot, 1.80 ng per spot, 3.80% for TP, respectively. The first analytical application for the determination of these compounds was developed. The recovery of standard samples added to commercial products chocolate, tea, coffee and aminophylline is in the range 92.80-106.08%. The proposed method was successfully applied to real sample analysis without separation.

Determination of thioguanine in pharmaceutical preparations by paper substrate room temperature phosphorimetry

A room temperature phosphorimetric (RTP) procedure was used for the determination of 6-thioguanine (6-TG). The method is based on paper substrate room temperature phosphorimetry (PS-RTP) using indium sulfate, In2(SO4)3 as a heavy atom perturber. Various factors affecting the room temperature phosphorescence of 6-TG are discussed. The linear dynamic range for 6-TG is from 3.3 to 334.3 ng per spot with a detection limit of 4.6 ng per spot and a relative standard deviation (RSD) of 2.38%. The recovery of standard 6-TG added to commercial tablets is in the range 96.39-98.44%. The method is simple, rapid and sensitive and can be applied to the analysis of commercial tablets without interference.

Spectroscopy behavior of 6-Mercaptopurine, Azathiopurine, and 8-Azaguanine

A comparative study, luminescence behavior of 6-Mercaptopurine (6-MP), Azathiopurine (BAN), and 8-Azaguanine (8-Azan) have been investigated including the low temperature phosphorescence, the low temperature fluorescence, the room temperature phosphorescence (RTP) and the room temperature fluorescence (RTF). The effect of pH on the luminescence intensity is discussed. Analytical characteristics of RTF and RTP of 6-MP, BAN, and 8-Azan have been studied. The lifetime of phosphorescence and the polarity of RTF and RTP have been examined.

Investigation on thioguanine by solid surface fluorimetry

ABSTRACT The solid surface fluorimetry (SSF) for the determination of 6-thioguanine (6-TG) has been presented. Several experimental conditions such as the type of solid substrate, pH of the medium, rigidity state of substrate, drying condition etc. were optimized. The new and highly sensitive procedure has a linear range of 3.3∼668.6ng/spot with the correlation coefficient 0.999, the relative standard deviation (RSD) 3.16% and the limit of detection 0.47 ng/spot corresponding to three times the standard deviation of the blank (n=11). The recovery of standard 6-TG added to urine was over the range of 97.4-107.4%. The method is simple, rapid and sensitive and can be applied to analysis of urine without interference.

A NOVEL CHEMOSENSOR FOR Fe(III) BASED ON PHOSPHORESCENCE QUENCHED 9-BROMOPHENANTHRENE INDUCED BY β-CYCLODEXTRIN COMBINED WITH FLOW INJECTION RENEWABLE DROP

A novel phosphorescent chemosensor for Fe(III) based on room-temperature phosphorescence (RTP) using the method of flow injection renewable drop (FIRD) was developed. A RTP of 9-bromophenanthrene (BrP) can be induced by β-cyclodextrin (β-CD) in the presence of cyclohexane (CH); however, trace Fe(III) caused a decrease of the RTP emission. The optimal conditions were investigated. Under the optimal conditions, the analytical curve of Fe3+ gave a linear dynamic range of 4.0 × 10−7 mol(L−1∼6.0 × 10−4 mol(L−1, with a detection limit of 36 μg/L. When the established CD-RTP method was applied to determine the concentrations of Fe(III) in synthetic samples, the experiment results demonstrated that the range of recovery was 97.3%–102%, with a relative standard deviation less than 2.05% (n = 6).

Controlled Release of Curcumin via Folic Acid Conjugated Magnetic Drug Delivery System

In the paper, folic acid(FA)-mediated and β-cyclodextrin(β-CD) derivatives functionalized magnetic Fe3O4 nanoparticles(MNPs) were successfully prepared as drug carriers for the targeted delivery and controlled release of water-insoluble anticancer drug. FA-sulfobutyl ether-β-CD-MNPs(FA-SBE-β-CD-MNPs), FA-hydroxypropyl-β-CD-MNPs(FA-HP-β-CD-MNPs) and FA-carboxymethyl-β-CD-MNPs(FA-CM-β-CD-MNPs) were fabricated, and the loading efficiency and relative entrapment rate of curcumin are 12.04 mg/g, 95.56% for FA-SBE-β-CD-MNPs, 9.6 mg/g, 81.63% for FA-HP-β-CD-MNPs and 7.88 mg/g, 85.28% for FA-CM-β-CD-MNPs, respectively. Meanwhile, at pH=5.0, the optimal release rate of curcumin is about 46.07% for FA-SBE-β-CD-MNPs in 5 h. Cellular uptake indicates that curcumin can be selectively transported to targeting site and released from the internalized carriers. The in vitro cytotoxicity reveals that non-toxic FA-SBE-β-CD-MNPs have excellent biocompatibility on HepG2 cells in the tested concentrations. Therefore, FA-SBE-β-CD-MNPs could provide a promising platform for the targeting delivery of water insoluble anti-cancer drugs for different treatment needs of cancer therapy.

A novel highly sensitive fluorescent probe based on Schiff base for Al 3

A facile Schiff-base ligand 8-hydroxyjulolidine-pyridyl hydrazone ( L ) as the fluorescent probe was synthesized and characterized. L was selective toward Al3+ ions with a visible color change from pale-to-yellow and fluorescence enhancement at 480 nm. L forms complex with Al3+ in 1:1 ratio as supported by Job’s plot analysis and ESI-MS. The binding mode was further confirmed by 1H NMR titrations. The detection limit was calculated to be 8.22×10−8 M for Al3+. These merits of L , i.e., requiring facile one-step synthesis and displaying high sensitivity make L a promising candidate as a chemosensor for Al3+ion.