Synthesis and fluorescence of novel complexes of tricyano-dihydrofuran and ofloxacin

Quinolones are widely used, but there are few reports on the application of fluorescent probe analysis. In this paper, we synthesized a tricyano-dihydrofuran (DCDHF-2-V) electron acceptor, and a (DCDHF-2-V)-quinolone fluorescent nanoprobe was designed. Its structure was characterized by infrared spectroscopy (IR), nuclear magnetic resonance (NMR) and ultraviolet (UV). A novel tricyano-dihydrofuran-ofloxacin fluorescent nanoprobe was established for the first time by fluorescence spectrophotometry. A novel fluorescent nanoprobe was obtained and used in the determination of ofloxacin in vitro. The results showed that tricyano-dihydrofuran can form stable charge transfer complex with ofloxacin, and it can be used for the determination of ofloxacin in drugs as a fluorescent probe. While important experimental steps are for the first time achieved in this study for future Quinolone fluorescent nanoprobe implementations, this method is simple and sensitive.

Solvothermal synthesis and characterization of well-dispersed cerium-doped Y2SiO5 phosphor particles

Well-dispersed cerium-doped Y2SiO5 (Ce:YSO) phosphor particles with spherical morphology and good luminescence intensity have been achieved by a solvothermal method with ethanol and water as solvent media. X-ray diffraction, Fourier transform infrared spectroscopy, fluorescence spectrophotometry and transmission electron microscopy were employed to characterize the as-synthesized Ce:YSO precursor and powders. The results showed that pure-phase Ce:YSO powders with a mean particle size of about 162 nm were accurately available at 310°C and above. The fluorescence ability and persistent luminescence decay properties of the Ce:YSO powders were also studied, and the excellent fluorescence properties could be attributed to the homogeneous Ce:YSO particles obtained through the solvothermal method.

A Highly Selective Economical Sensor for 4-Nitrophenol

Herein, an inexpensive commercially available sensor is presented for the detection of 4-nitrophenol (4NP) pollutant. Sodium fluorescein (NaFl) is used as a sensor to detect trace amounts of 4NP in acetonitrile (MeCN). The photophysical properties of NaFl were studied in two different solvents, MeCN (aprotic) and water (protic), with varying concentrations of different nitroaromatics using UV-visible absorption and fluorescence spectrophotometry. In an aqueous medium, photophysical properties of NaFl did not change in the presence of nitroaromatics. However, examination of the photodynamics in MeCN demonstrated that NaFl is extremely sensitive to 4NP (limit of detection: 0.29 µg/mL). This extreme specificity of NaFl towards 4NP when dissolved in MeCN, as compared to other nitroaromatics, is attributed to hydrogen bonding of 4NP with NaFl in the absence of water, resulting in both static and dynamic quenching processes. Thus, NaFl is demonstrated as a simple, inexpensive, sensitive, and robust optical turn off sensor for 4NP.

A 1-Hydroxy-2,4-Diformylnaphthalene-Based Fluorescent Probe and Its Detection of Sulfites/Bisulfite

A novel 1-hydroxy-2,4-diformylnaphthalene-based fluorescent probe L was synthesized by a Knoevenagel reaction and exhibited excellent sensitivity and selectivity towards sulfite ions (SO32−) and bisulfite ions (HSO3−). The detection limits of the probe L were 0.24 μM using UV-Vis spectroscopy and 9.93 nM using fluorescence spectroscopy, respectively. Furthermore, the fluorescent probe L could be utilized for detection in real water samples with satisfactory recoveries in the range 99.20%~104.30% in lake water and 100.00%~104.80% in tap water by UV-Vis absorption spectrometry, and in the range 100.50%~108.60% in lake water and 102.70%~103.80% in tap water by fluorescence spectrophotometry.

Optimization of a Digestion Method to Determine Total Mercury in Fish Tissue by Cold Vapor Atomic Fluorescence Spectrophotometry

Several microwave-assisted digestion methods were tested at the Centro de Estudios Aplicados en Química laboratory in Quito, Ecuador, to determine the accuracy and performance efficiency of the mineralization process for the determination of total mercury in fish tissue by cold vapor atomic fluorescence spectrophotometry. The use of MARSEasyPrep high-pressure vessels, low amounts of reagents (1 cm3 HNO3, 1 cm3 H2O2, and 1 cm3 HClO4), an irradiation temperature of 210 °C, and 35 min of mineralization time resulted in accurate performance, with recoveries of certified reference material DORM-4 between 90.1% and 105.8%. This is better than the Association of Official Analytical Chemists 2015.01 method, which has a reported accuracy of 81%. The repeatability precision and intermediate precision were established at three concentration levels (0.167, 0.500, and 0.833 mg·kg−1) and expressed as the percentage of the relative standard deviation ranging from 1.5% to 3.0% and 1.7% to 4.2%, respectively. Further, the method was satisfactorily applied to analyze fortified samples of tilapia (Oreochromis niloticus), with recoveries ranging from 98.3% to 104.3%. The instrumental limits of detection and quantification were 0.118 µg·dm−3 and 0.394 µg·dm−3, respectively.

Quantification of Riboflavin and Pyridoxine in a Mixed Solution at a High Concentration by Fluorescence Spectrophotometry

A new method of quantifying the contents of riboflavin (RF) and pyridoxine (PY) in their mixed solution was introduced in this study. A mathematical model was established to calculate the actual concentration of PY (Z) based on the apparent concentrations of PY (Y) and RF (X), which were quantified directly when RF and PY were mixed together. First, a linear relationship was found between Y and Z with a high coefficient, which defines fluorescence quenching efficiency. Second, a curvilinear equation was established between the apparent concentration of X and the fluorescence quenching efficiency (k) of PY. The actual concentration of PY could be obtained by using the two equations. The established mathematical model was verified, and the relative error of the calculated PY value was below 2.5%. The upper limit of fluorescence spectrophotometry quantification was up to 20 μg/mL for both RF and PY. Compared with RP-HPLC, this method is convenient in terms of sample pretreatment, as well as saves organic solvents and time.