Thin-layer chromatographic separation and analysis of polynuclear aza heterocyclic compounds

Many thin-layer Chromatographic systems can be used for the general separation of aza heterocyclic compounds from polynuclear aromatic hydrocarbons. Several can be used for the separation of the aza compounds from each other. With alumina as the adsorbent the sterically hindered aza heterocyclic compounds can be readily separated from the non-hindered aza compounds.The use of the trifluoroacetic acid spot test on the thin-layer plate is discussed. Spectral data for the aza compounds are presented and discussed.     

Gel elution of heterocyclic analogues of polynuclear aromatic hydrocarbons from bio-beads

The Chromatographic elution characteristics from Bio-Beads SX-12 gel are reported for a wide range of polynuclear aromatic hydrocarbons and some of the heterocyclic analogues with which they are frequently associated in the environment. The use of benzene as solvent allows absorption effects to take place on the gels in the absence of hydrogenbonding effects. The elutions observed are discussed in terms of the contribution of the heteroatom to the gel elution effects.     

Direct coupling of column chromatography and thin-layer chromatography

Summary A system has been developed by which a chromatographic column is directly coupled to a TLC plate. The column effluent is divided by means of a variable splitter, the smaller portion being used for automatic spotting on the start line of a thin-layer plate; the larger portion is collected in fraction tubes, as usual. Provisions have been made by which the positions of the TLC spots can easily be correlated with the corresponding fraction tubes. The apparatus may be left without attendance to operate overnight. Several examples are described.

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Direkte Kupplung von Säulen- und Dünnschicht-Chromatographie

Zusammenfassung Bei dem beschriebenen Verfahren wird die säule direkt mit einer DC-Platte gekoppelt, indem der Eluatstrom mit Hilfe eines variablen Teilers in zwei Ströme aufgeteilt wird. Der kleinere wird automatisch auf die Startlinie einer DC-Platte aufgetragen, während der größere Teilstrom wie gewöhnlich in Reagensgläsern eines Fraktionensammlers aufgefangen wird. Die Apparatur ermöglicht es, für jede Fraktion einen zugehörigen Fleck auf die Dünnschichtplatte aufzutragen. Man kann die Vorrichtung auch nachts ohne Überwachung arbeiten lassen. Mehrere Anwendungsbeispiele werden beschrieben.

     

Study of air pollution particulates by X-ray photoelectron spectroscopy

Summary This paper discusses the application of X-ray photoelectron spectroscopy to the determination of the chemical composition of sulfur and nitrogen species in air pollution particulates. Core electron chemical shift measurements are augmented by the determination of relative concentrations and volatility of particulate species.

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Untersuchung von Verunreinigungsteilchen in der Luft durch Röntgenphotoelektronen-Spektroskopie

Zusammenfassung Die Anwendung der Röntgenphotoelektronen-Spektroskopie auf die Bestimmung der chemischen Zusammensetzung von Schwefel und Stickstoff enthaltenden Verunreinigungsteilchen in Luft wird diskutiert. Messungen der chemischen Verschiebung werden ergänzt durch die Bestimmung der relativen Konzentrationen und der Flüchtigkeit der Verbindungen.

Presented at the 6th Annual Symposium on Recent Advances in the Analytical Chemistry of Pollutants, April 21–23, 1976; Vienna, Austria.     

Distribution of n-alkanes, polynuclear aromatic hydrocarbons and nitrated polynuclear aromatic hydrocarbons between the fine and coarse fractions of inhalable atmospheric particulates.

The distribution ratios of n-alkanes, polynuclear aromatic hydrocarbons (PAHs) and nitrated PAH components between fine and coarse fractions of soot has been investigated in downtown Rome through three field campaigns carried out at different times of the year. The preferential accumulation of almost all species investigated onto fine particles has been observed in all field experiments performed. Moreover, nitrated PAHs had varied distributions, according to the origin of their occurrence in the atmosphere; in fact, congeners of photochemical origin accumulated more in fine particles than those released by primary sources.     

Detection of cations separated by thin-layer chromatography by fluorescence quenching of ethidium bromide

Cations such as Cu²⁺, Cr³⁺ and Hg⁺ can be separated on silica gel thin layer Chromatographic plates. The developing solution contains 0.02M EDTA at pH 2.5. For visualization, the plate was pretreated with ethidium bromide, a strong fluorescer. Quenching of the red fluorescence can be observed visually even down to the 0.1 nmole range per spot.     

Direct secondary-ion mass spectrometric analysis of mixtures separated by thin-layer chromatography and electrophoresis

Secondary-ion mass spectrometry (SIMS) is used to sputter ions directly from thin-layr chromatograms in which components in a mixture have been separated. Mixtures of phenothiazine drugs and small peptides have been separated an detected by the chromatography/SIMS method. Phosphonium salts have been separated by thin-layer chromatography and imaged in situ by mass spectrometer. Organometallic compounds such as the transition metral acetylacetonates have been simialry determined. Mixtures that have been separated by gel electrophoresis are transferred by using a standard blotting procedure to a nitrocellulose support, which is then examined by secondary-ion mass spectrometry. A mixture of organic dyes was separated by gel electrophoresis, and characterized by secondary-ion mass spectrometry. The use of the mass spectral information to deconvolute overlapping components on the chromatogram is discussed, and the ultimate spatial resolution for molecular mapping is estimated as about 1 μm.     

Determination of polynuclear aromatic hydro-carbons and mononitrated derivatives in air and diesel particulates

A method is described for the determination of three- to six-ring polynuclear aromatic hydro-carbons (PAHs) and mononitrated PAHs (nitro-PAHs) in particulate matter. The procedure includes Soxhlet extraction followed by fractionation using gel filtration chromatography and normal-phase liquid chromatography with an aminosilane stationary phase. The resulting fractions were separated by capillary gas chromatography (GC) into individual PAHs and nitro-PAHs which were detected by a flame-ionization detector and a thermal energy analyzer, respectively. Commercially available standards were used for quantification. Individual peak assignments were confirmed by using both mass spectral and retention index data obtained through computerized capillary GC-mass spectrometry. Several samples were processed, including a certified diesel particulate reference material supplied by the National Bureau of Standards for the purpose of evaluating analytical methods. This method may also be applicable in the determination of certain carbonyl PAHs.     

Determination of polynuclear aromatic hydrocarbons in environmental samples by Micellar liquid chromatography

A method for the separation of polycyclic aromatic hydrocarbons (PAHs) by high-performance liquid chromatography using a hybrid micellar mobile phase is described. The detection of PAHs was carried out using the fluorescence method with programmable excitation and emission wavelength. The method is applied to the analysis of several environmental samples (sea water, sediments, limpets, sea worms) and several of these compounds are quantitated at concentration below 70 ng L⁻¹(kg⁻¹) in the original samples.     

Quantitation and identification of polynuclear aromatic hydrocarbons by liquid chromatography and multiwavelength absorption spectrometry

This paper describes the combined use of liquid chromatographic separation with multiwavelength absorption detection for the quantitation and identification of polynuclear aromatic hydrocarbons. Quantiative results are presented for three- and four-component mixtures with complete and partial separation. Qualitative data are presented for a twelve-component synthetic mixture and for extracts from a filter used to collect particulate emissions from a biomass-gasifier system. It is shown that multiwavelength data-processing methods commonly applied to absorption spectra can be applied with significant advantage to second-derivative spectra. Results indicate that significant improvements can be achieved by the use of different wavelength ranges for different components in mixtures. Detection limits for single-component samples varied between 3 and 11 μg l^?1 for eleven hydrocarbons and the scatter about calibration plots for mixtures was in the range of 0.05 to 0.4 μg ml^?1. The identities of all twelve components in the synthetic mixture were confirmed and nineteen components were identified in the sample from the biomass gasifier filter.     

Isotope analysis of hydrocarbons: trapping, recovering and archiving hydrocarbons and halocarbons separated from ambient air

It is argued that isotope analysis of atmospheric non-methane hydrocarbons (NMHCs) and, in particular, the analysis of the deuterium/hydrogen (D/H) ratio is valuable because the dominant self-cleansing property of the troposphere is based on the OH radical which removes, e.g., CH4 and other alkanes by H-atom abstraction, which induces large kinetic isotope effects. The major obstacle in applying D/H isotope analysis to atmospheric NMHCs is not only the low abundance of D itself but, in particular, the low concentrations of NMHCs in the parts per trillion range. We show how a selection of NMHCs can be quantitatively separated from 300 L air samples together with CO2 as carrier gas matrix, by using high efficiency cryogenic traps. After diluting the extracted NMHC mixtures with hydrocarbon free air, and determining the mixing ratios, good agreement with original whole air sample analysis exists for alkanes and several halocarbons. For unsaturated hydrocarbons and some other halocarbons the extraction and recovery yield under the given conditions fell considerably, as a function of boiling point. Furthermore, the mixture of NMHCs in the CO2 matrix is proven to remain unchanged over several years when conveniently stored in glass ampoules. The 'extracts' or 'concentrates' of condensables extracted from larger air samples will enable the D/H isotope analysis of ultra trace gases in the atmosphere.