Photoluminescence spectroscopy of anthrathiophenes and benzonaphthothiophenes in Shpol'skii matrixes

The dispersion of harmful oil components into the ocean waters could pose long-term risks to flora and fauna. Due to the complexity of oil-contaminated sites, the unambiguous identification and quantitation of environmental pollutants often requires the sequence of high-performance liquid chromatography and gas chromatography-mass spectrometry. A classic example is the analysis of polycyclic aromatic hydrocarbons. This article tackles a different aspect of environmental analysis as it focuses on the Shpol'skii spectroscopy of polycyclic aromatic sulfur heterocycles, specifically those belonging to the subgroups often known as anthrathiophenes and benzonaphthothiophenes. Photoluminescence measurements were made with a commercial spectrofluorimeter equipped with a continuous wave excitation source for steady state measurements and a pulsed excitation source for time-resolved measurements in the phosphorescence time domain. To the extent of our literature search, this is the first report on the 4.2 K fluorescence and phosphorescence spectra of anthrathiophenes and benzonaphthothiophenes, and the 77 K and 4.2 K phosphorescence lifetimes of benzonaphthothiophenes. 77 K and 4.2 K analytical figures of merit revealed the possibility to detect the studied compounds at the parts-per-billion (ng mL^-1) concentration levels. The spectral and lifetime data gathered in this article provides the required information to choose an appropriate photoluminescence technique for the analysis of four-ring polycyclic aromatic sulfur heterocycles in complex environmental extracts.

Laser-induced multidimensional fluorescence spectroscopy in Shpol'skii matrixes with a fiber-optic probe at liquid helium temperature

Improved methodology for chemical analysis via laser-excited Shpol'skii spectrometry at liquid helium temperature (4.2 K) is reported. Sample freezing is performed in a matter of seconds with the aid of a fiber-optic probe directly inserted into the liquid cryogen. Emission wavelength time matrixes, excitation emission wavelengths, and time-resolved excitation emission wavelengths are rapidly collected with the aid of a pulsed tunable dye laser, a high-resolution spectrograph, and an intensified charged-couple device. Data reproducibility for qualitative and quantitative analysis purposes and analytical figures of merit are demonstrated for several polycilic aromatic hydrocarbons/n-alkane systems. Fluorescence lifetime differences from analyte molecules occupying different crystallographic sites in the same frozen matrix are presented for the first time. The potential of our approach is illustrated for the direct analysis of a benzopyrene fraction typically encountered in HPLC analysis of polycyclic aromatic hydrocarbons.

Solid-liquid extraction laser excited time-resolved Shpol'skii spectrometry: a facile method for the direct detection of 15 priority pollutants in water samples

A unique method for monitoring polycyclic aromatic hydrocarbons is reported for routine analysis of water samples. The assay consists of a three-step procedure. One hundred milliliters of water is processed through an octadecyl extraction membrane via solid-liquid extraction. The pollutants are eluted with 5 mL of n-hexane and directly determined in the eluting solvent by laser excited time-resolved Shpol'skii spectrometry. Seventy-seven K fluorescence measurements are made with the aid of an optical fiber probe that avoids the complications of classical low-temperature methodology. The total analysis time from the extraction to PAH identification is approximately 5 min per sample. Limits of detection are at the subparts per billion levels. The simplicity of the experimental procedure, the short analysis time, the selectivity, and the excellent analytical figures of merit demonstrate the advantages of this approach for routine analysis of water samples.

Polymerized fluorescent liposomes incorporating lanthanide ions

This paper describes the design and synthesis of a polymerizable lipid capable of complexing lanthanide ions. The lipid has been successfully incorporated into liposomes and then polymerized. Fluorescence studies indicate that the diacetylene (unpolymerized lipid) and the conjugated alkenes (after polymerization) can be used as sensitizers for the lanthanide ion.

Synthesis and fluorescence properties of new fluorescent, polymerizable, metal-chelating lipids

Liposomes incorporating fluorescent, metal-chelating lipids find applications in molecular recognition of peptides, 2D protein recrystallization, protein targeting, and biological sensing. It would be advantageous to combine the usefulness of polymerizable, metal-chelating lipids and fluorescent lipids. Herein, we report the synthesis and fluorescence properties of several fluorescent, polymerizable, metal-chelating lipids. They have been successfully incorporated into liposomes and then polymerized. These lipids can be used as membrane probes to study the polymerizable liposomes in the unpolymerized state and to investigate lipid redistribution during polymerization. In addition, if a luminescent metal ion (e.g., Eu(3+), Tb(3+), etc.) is used to complex the headgroup, the lipids can probe the membrane interior and exterior simultaneously.

Phosphorimetric determination of indomethacin in pharmaceutical formulations

A simple, rapid and sensitive method for the determination of indomethacin was developed based on solid-surface room-temperature phosphorimetry. Phosphorescence emission was induced by the indomethacin hydrolysis reaction in a basic medium. Chromatography paper treated for background reduction was employed as a solid substrate. The use of four heavy-atom salts and sodium dodecyl sulfate was optimized to estimate an absolute limit of detection at the subnanogram level. A calibration curve with a linear dynamic range extending over two orders of magnitude (3.0 x 10(-7)-1.0 x 10(-4) mol dm-3) was obtained. The recovery of the method (98.4 +/- 6.8%) was tested using commercial formulations containing indomethacin as the only anti-inflammatory agent.

Solid-surface room-temperature phosphorescence detection of serotonin, tryptamine, and gramine enhanced by inorganic salts and sodium dodecyl sulfate

Room-temperature phosphorescence characteristics of serotonin (5-hydroxytryptamine), typtamine, and gramine ([3-(dimethylaminomethyl)indole]) were studied on low-background paper substrates. Several experimental parameters were optimized for maximum signal intensity. Sodium iodide, thallium(I) nitrate, silver(I) nitrate, and lead(II) nitrate were tested as phosphorescence enhancers. The effect of sodium dodecyl sulfate on the enhancement efficiency of these inorganic salts was also studied. The pH values of the solutions were adjusted to optimize the interaction between analyte molecules and solid substrates. Under the experimental conditions for maximum phosphorescence intensity, working curves ranging from two (gramine) to four (typtamine) orders of magnitude were obtained. Limits of detection at the nanogram level were estimated for the three compounds, showing the potential of solid-surface room-temperature phosphorimetry as a detection technique for biogenic amines.

Solid-surface room-temperature phosphorescence detection for high-performance liquid chromatography

In the present study, we have optimized the use of a two nebulizer system for solid-surface room-temperature phosphorescence (SSRTP) as a selective, permanent record detector for high-performance liquid chromatography (HPLC). The chromatographic parameters and the analytical figures of merit of five well known phosphorescent compounds were compared to those obtained by ultraviolet detection. Calibration curves with satisfactory linear dynamic ranges and limits of detection in the nanogram and subnanogram level showed the feasibility of the SSRTP detector for HPLC. In addition, overlapped compounds were individually identified demonstrating that the selectivity of the proposed detector can be a useful feature in case of incomplete chromatographic separations of complex mixtures.

Mixture analysis and quantitative determination of nitrogen-containing organic molecules by surface-enhanced Raman spectrometry

Surface-enhanced Raman spectrometry (SERS) on a silver-coated filter paper substrate of nitrogen-containing organic molecules is reported. A correction procedure for standardization of measurements is proposed and evaluated to solve the difficult problem of quantitation of adsorbate in SERS. The relative standard deviation obtained through this procedure is around 15%. Linearity (r = 0.999) was achieved up to 50 micrograms/mL aminoacridine. A limited dynamic range is observed, however, due to the limited number of SERS active sites in the substrate. Spectral fingerprinting of three-component mixtures by concentration-dependent selective molecular adsorption on the substrate is also reported.