Combining cryogenic fiber optic probes with commercial spectrofluorimeters for the synchronous fluorescence Shpol'skii spectroscopy of high molecular weight polycyclic aromatic hydrocarbons

Low-temperature time-resolved phosphorescence excitation emission matrices for the analysis of phenanthro-thiophenes in chromatographic fractions of complex environmental extracts

The present study investigates the analytical potential of low-temperature photoluminescence spectroscopy for the analysis of seven phenanthrothiophenes with molecular mass 234 g mol^-1. The studied PASHs include Phenanthro [1,2-b]thiophene, Phenanthro [2,1-b]thiophene, Phenanthro [2,3-b]thiophene, Phenanthro [3,2-b]thiophene, Phenanthro [3,4-b]thiophene, Phenanthro [4,3-b]thiophene and Phenanthro [9,10-b]thiophene. Excitation and emission spectra recorded from n-alkane solutions at room temperature, 77 K and 4.2 K show phosphorescence emission from all the studied isomers at cryogenic temperatures. The analytical figures of merit obtained under steady state (fluorescence) and time-resolved (phosphorescence) conditions provide limits of detection at the parts-per-billion (ng mL^-1) concentration levels. Processing 77 K and 4.2 K phosphorescence data with parallel factor analysis showed to be a robust approach to the determination of phenanthro-thiophenes in complex fluorophore mixtures.

Analysis of various solid samples by synchronous fluorescence spectroscopy and related methods: A review

This critical Review covers the literature reports on analysis of different types of solid samples by the synchronous fluorescence spectroscopy (SFS) and its varieties, which include synchronous phosphorescence spectroscopy and synchronous luminescence spectroscopy, in the three decades (1990-2019). Both the qualitative and quantitative spectroscopic analysis is described for a wide range of specimens. Their physical forms and chemical composition include: a) organic and inorganic analytes pre-concentrated from solution on matrices (beads, membranes, filters, disks, paper), b) natural and synthetic multi-component specimens of complex composition (biological tissues, soil, polymers) and c) inorganic and coordination compounds including porous materials and particularly metal-organic frameworks (MOFs). The comparison with the data obtained by "conventional" optical emission spectroscopy and other analytical techniques (when available) is presented. The specific advantages of the high-resolution varieties of the method, the first- and second-derivative solid-state synchronous fluorescence, luminescence, and phosphorescence spectroscopy are described. An attention is also paid to practical conditions of the typical tests, and the relevant experimental setups. The impetus is on the emerging capabilities of this highly promising method e.g. in-situ monitoring of chemical reactions, in-vivo diagnostics, surface reactions, and detection of the adsorbate. The existing challenges are analyzed, and the unexplored application "niches" to further develop this and the related analytical methods are revealed. 145 references, 9 Tables, 17 Figures and 1 Scheme.

Determination of polycyclic aromatic hydrocarbons with molecular mass 302 in Standard Reference Material 1597a by reversed-phase liquid chromatography and stop-flow fluorescence detection

The identification of isomeric polycyclic aromatic hydrocarbons (PAHs) in complex samples via reversed-phase liquid chromatography (RPLC) with fluorescence detection (FL) is normally based on matching the chromatographic retention times of suspected peaks of interest with reference standards. Since no spectral information is obtained during the chromatographic run, the accurate identification of co-eluting PAHs with similar chromatographic behaviors requires confirmation with additional chromatographic methods. This is particularly true for the analysis of PAH isomers with the relative molecular mass (MM, g/mol) 302. The work presented here explores the information content of room-temperature fluorescence spectra for the analysis of PAHs with MM 302 in the Standard Reference Material (SRM) 1597a. Fluorescence spectra were recorded under stop-flow conditions with the aid of a commercial HPLC system. Of the 21 MM 302 PAHs known to be present in the SRM 1597a, 20 were tentatively identified based on retention times and the presence of 18 was confirmed based on excitation and emission spectral profiles.

Determination of high-molecular weight polycyclic aromatic hydrocarbons in high performance liquid chromatography fractions of coal tar standard reference material 1597a via solid-phase nanoextraction and laser-excited time-resolved Shpol'skii spectroscopy

This article presents an alternative approach for the analysis of high molecular weight - polycyclic aromatic hydrocarbons (HMW-PAHs) with molecular mass 302 Da in complex environmental samples. This is not a trivial task due to the large number of molecular mass 302 Da isomers with very similar chromatographic elution times and similar, possibly even virtually identical, mass fragmentation patterns. The method presented here is based on 4.2K laser-excited time-resolved Shpol'skii spectroscopy, a high resolution spectroscopic technique with the appropriate selectivity for the unambiguous determination of PAHs with the same molecular mass. The potential of this approach is demonstrated here with the analysis of a coal tar standard reference material (SRM) 1597a. Liquid chromatography fractions were submitted to the spectroscopic analysis of five targeted isomers, namely dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene, naphtho[2,3-a]pyrene and dibenzo[a,h]pyrene. Prior to analyte determination, the liquid chromatographic fractions were pre-concentrated with gold nanoparticles. Complete analysis was possible with microliters of chromatographic fractions and organic solvents. The limits of detection varied from 0.05 (dibenzo[a,l]pyrene) to 0.24 µg L(-1) (dibenzo[a,e]pyrene). The excellent analytical figures of merit associated to its non-destructive nature, which provides ample opportunity for further analysis with other instrumental methods, makes this approach an attractive alternative for the determination of PAH isomers in complex environmental samples.