HPLC determination of acetaminophen in saliva based on precolumn fluorescence derivatization with 12-(3,5-dichloro-2,4,6-triazinyl)benzo[d]benzo[1',2'-6,5]isoindolo[1,2-b][1,3]thiazolidine.

A high-performance liquid-chromatographic method for the determination of acetaminophen in saliva has been developed. This method is based on the precolumn derivatization of acetaminophen with 12-(3,5-dichloro-2,4,6-triazinyl)benzo[d]benzo[1',2'-6,5]isoindolo[1,2-b][1,3]thiazolidine, a new fluorescence derivatization reagent for phenolic compounds. The resulting derivative of acetaminophen is separated by isocratic elution on a reversed-phase column, and is fluorometrically detected at an emission wavelength of 560 nm with an excitation wavelength of 540 nm. The detection limit (signal-to-noise ratio = 3) was 0.1 microg/mL in saliva. The proposed method permits a highly sensitive and simple determination of acetaminophen in a small amount of saliva without any sample purification.     

The multicomponent reaction of imidazo[1,5-a]pyridine carbenes with phthalaldehydes and dimethyl acetylenedicarboxylate: a facile construction of benzo[d]furo[3,2-b]azepines

A study on the multicomponent reaction comprising both N-heterocyclic carbenes and substituted phthalaldehydes is reported. The imidazo[1,5-a]pyridine carbenes, namely imidazo[1,5-a]pyridine-3-ylidenes, reacted with phthalaldehydes and DMAD under very mild conditions to produce novel fused tricyclic benzo[d]furo[3,2-b]azepine derivatives. The resulting fused heterocyclic compounds are fluorescent and they give an emission around 500 nm with quantum yields (Φ(F)) being up to 0.81. This study provides not only a unique approach to fused azepine derivatives that are not easily accessible by other methods, but also opens a new avenue to complicated molecular skeletons. The fluorescence properties of long emission wavelength and high fluorescence quantum yields of some products predict their potential applications as optical sensors.     

Measurement of benzo[a]pyrene,benzo[k]fluoranthene and benzo[g,h,i]perylene by ultraviolet spectroscopy

Microchimica Acta - The technique for determining benzo[a]pyrene, benzo[k]fhuoranthene, and benzo[g,h,i]perylene respectively inμg amounts by UV absorption measurements is described. The...     

Development of a highly sensitive monoclonal antibody based ELISA for detection of benzo[a]pyrene in potable water

In Europe, a limit value of 10 ng L(-1) was set by the European Commission for benzo[a]pyrene (B[a]P) in water intended for human consumption (Council Directive 98/83/EC) and, therefore, sensitive and reliable methods are needed to evaluate its presence. We report here on the development of a highly sensitive indirect competitive ELISA for the detection of B[a]P in potable water. Fourteen monoclonal antibodies were generated in mice using novel B[a]P derivatives. The immunoassay with the least interference and the best sensitivity was optimized and characterized. As co-solvent, ten percent methanol (v/v) was determined as the optimum concentration for B[a]P solubilization for use with the developed ELISA. With the purified antibody (clone 22F12) the average IC50 for B[a]P and corresponding detection limit at a signal:noise (S/N) ratio of 3 was 65 ng L(-1) and 24 ng L(-1), respectively. From the 16 EPA-designated PAHs, only chrysene, indeno[1,2,3-cd]pyrene, and benzo[b]fluoranthene showed a cross-reactivity (CR) higher than 20%. No CR was observed for two- and three-ringed aromatics as well as dibenz[ah]anthracene and benzo[ghi]perylene. The effect of pH value (range 6.5-9.5), ionic strength (specific electric conductivity 1 microS cm(-1)-2.5 mS cm(-1)), and inorganic ions (sodium, copper, iron, aluminium, manganese, chloride, sulfate, nitrate, and nitrite at maximum permissible levels according to the Council Directive) on both signal and sensitivity of the ELISA was studied. No significant influence of these parameters on the ELISA competition curve was found. We suggest that the optimized ELISA can be used to monitor potable water samples without previous extraction from the samples. The assay should facilitate the cleanup of B[a]P contaminated sites where B[a]P levels fall close to the limit value of the new drinking water directive.     

Admicelle-enhanced synchronous fluorescence spectrometry for the selective determination of polycyclic aromatic hydrocarbons in water

A simple and rapid method for the highly sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in water was developed. Benzo[a]pyrene, benzo[k]fluoranthene, perylene, and pyrene in water were concentrated into sodium dodecyl sulfate (SDS)-alumina admicelles. The collection was performed by adding SDS and alumina particles into the sample solution at pH 2. After gentle mixing, the resulting suspension was passed through a membrane filter to collect the SDS admicelles containing highly concentrated PAHs. The filter was placed on a slide glass and then covered admicellar layer with a fused silica glass plate before setting in a fluorescence spectrometer. Benzo[a]pyrene, benzo[k]fluoranthene, perylene, and pyrene were selectively determined by the synchronous fluorescence scan (SFS) analysis with keeping wavelength intervals between excitation and emission to 98, 35, 29, and 45 nm, respectively. Because of the minimum spectral overlapping, 1-40 ng l⁻¹ of benzo[a]pyrene, benzo[k]fluoranthene, and perylene as well as 10-150 ng l⁻¹ of pyrene were selectively determined with eliminating the interferences of other 12 PAHs. The detection limits were 0.3 ng l⁻¹ for benzo[a]pyrene, benzo[k]fluoranthene, and perylene, and 1 ng l⁻¹ for pyrene. They were 2-3 orders of magnitude lower than the detection limits in normal aqueous micellar solutions. The application to water analysis was studied.     

The determination of benzo[a]pyrene in the total particulate matter of cigarette smoke

A procedure for the isolation and determination of benzo[a]pyrene in the total particulate matter of cigarette smoke is described. Two high-pressure liquid chromatographic (HPLC) techniques are employed: a normal-phase, mu Bondapak-NH2, amino column is used for isolation of the benzo[a]pyrene fraction and a reversed-phase, Vydac 201TP54, polymeric octadecyl silane column is used for quantitation. Fluorescence detection is used in both modes of chromatography. The wavelengths of excitation and emission are evaluated for analytical detection. Extraction media and various isolation techniques are compared for their extraction efficiency and isolation from interferences, respectively. The procedure is efficient, reproducible, sensitive (3 pg), and gives results that compare favorably with other techniques reported in the literature for the B[a]P content of reference cigarettes, 1R1 and 1R4F.     

Resolution of 13 polycyclic aromatic hydrocarbons by constant-wavelength synchronous spectrofluorometry.

A method capable of determining 13 PAHs (acenaphthene, anthracene, benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, dibenzo[ah]anthracene, fluoranthene, fluorene, indene[1,2,3-cd]pyrene, phenanthrene and pyrene) in a mixture of 16 EPA PAHs by second derivative synchronous spectrofluorometry in the constant wavelength mode was developed. It has not been possible to determine the following PAHs in the mixture: acenaphthylene, benzo[ghi]perylene and naphthalene. The approach studied allows the sensitive, rapid and inexpensive identification and quantitation of 13 PAHs in a solution of hexane. The detection limits are <1 microg L(-1) (except for chrysene and phenanthrene).     

A simple method for the determination of benzo[a]pyrene and benzo[k]fluoranthene in a mixture

Atmospheric particulate matter is routinely analysed for the concentration of the carcinogen benzo[a]pyrene (BaP). Benzo[k]fluoranthene (BkF) has identical spectral characteristics and interferes in the fluorimetric estimation. A simple method for the determination of BaP in the presence of BkF is described. Based on quenching of the fluorescence of BaP by the addition of small amounts of nitromethane, the method can be used for accurate estimation for wide concentration ratios of BaP to BkF ranging from 0.1 to 10.0.     

四[4,4'-双(4",4",4"-三氟代-1",3"-二氧代丁基)邻三联苯]双核铕配合物的发光及其在发光二极管中的应用

合成了一个双核铕的配合物,[HN(CH3CH2)3]2[Eu2(bdb)4]·CH3CH2OH,{H2bdb=4,4'-双(4",4",4"-三氟代-1",3"-二氧代丁基)邻三联苯}.该配合物在紫外和近紫外光激发下发出铕离子特征红光.配合物中三价铕离子的5D0激发态寿命为704μs,寿命曲线很好地和单指数衰减拟合曲线相吻合.监控614nm的红光发射,激发光谱位于250～420nm范围.在395nm处具有很强的激发强度,该配合物能够被395nm发射的InGaN芯片发出的近紫外光激发而发红光.变温光致发光测定表明,该配合物的温度淬灭效应很小.当温度升高到200℃,依然发射出很强的红光.配合物热稳定性达到260℃.发光性质和热稳定性满足制备LED器件的要求.将该配合物与395nm发射的InGaN芯片组合制备了红色发光二极管,当配合物和硅树脂的质量比为1:20,工作电流为20mA时,红色发光二极管的色坐标为x=0.61,y=0.31,发光效率为3.64lm/W.将该配合物与发蓝绿光的二-2-(2'-羟基苯基)苯并噻唑锌混合涂布在395nm发射的InGaN芯片上制备成了白光发光二极管,合适的质量比为铕配合物:锌配合物:硅树脂=1:1:25.工作电流为20mA时,色坐标x=0.32,y=0.32;色温Tc=6026K;显色指数Ra=81;发光效率为1.26lm/W.结果表明,该配合物是制备半导体高显色指数白光LED的一种红光材料.     

Second-derivative constant-wavelength synchronous scan spectrofluorimetry for determination of benzo[b]fluoranthene, benzo[a]pyrene and indeno[1,2,3-cd]pyrene in drinking water

The use of derivative constant-wavelength synchronous scan fluorimetry is reported for the determination of three polycyclic aromatic hydrocarbon pollutants in drinking water (linearity range 0.4-4 mug 1(-1)). The limits of detection (LD) and quantification (LQ) (mug 1(-1)) are 0.01 and 0.07 for benzo[b]fluoranthene, 0.03 and 0.12 for benzo[a]pyrene and 0.19 and 0.57 for indeno[1,2,3-cd]pyrene in the presence of three other pollutants, benzo[k]fluoranthene, benzo[ghi]perylene and fluoranthene. The precision (RSD /= 85%) were satisfactory.     

Separation and identification of polar degradation products of benzo[a]pyrene with ozone by atmospheric pressure chemical ionization-mass spectrometry after optimized column chromatographic clean-up.

The environmental relevance of oxidized degradation products of polycyclic aromatic hydrocarbons (PAHs) increases due to enhanced combustion of organic matter and fossil fuels. For PAHs consisting of more than three condensed aromatic rings, soot aerosols are the main carrier, on the surface of which they can react with trace gases like ozone. In this study the clean-up procedure and analysis of ozonized benzo[a]pyrene (B[a]P) was optimized. B[a]P and its degradation products were preseparated into three fractions. Different reversed-phase materials were evaluated for high-performance liquid chromatographic separation. Among these, a phenyl-modified silica material proved best-suited and the chromatographic separation was optimized on this material. For the detection of separated degradation products, liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry (LC-APCI-MS) was used. With this method, 29 components could be characterized. Besides the three known main degradation products (B[a]P-1,6-dione, B[a]P-3,6-dione, B[a]P-6,12-dione, B[a]P-4,5-dione and 4-oxa-benzo[d,e,f]chrysene-5-one (B[def]C-lactone), were identified for the first time with the help of reference substances. B[def]C-lactone is known as a substance with a mutagenic potential similar to B[a]P. Several other compounds could be tentatively identified.     

Determination of benzo[a]pyrene in shale oil-by solid-surface fluorescence

A method has been developed for determining benzo[a]pyrene in shale oil by combining dry-column chromatography, thin-layer chromatography and fluorescence spectrometry. A two-step separation method was employed to isolate benzo[a]pyrene from shale oil. Benzo[a]pyrene was identified and determined by detecting its fluorescence directly from chromatoplates; as little as 0.06 ng can be detected. The limit of detection of benzo[a]pyrene in shale oil is ca. 1.2 ppm and the reproducibility of the method is ±2.6 ppm.     

A facile route to water-soluble coronenes and benzo[ghi]perylenes

Click reactions at the bay-position of perylenes and a new route to benzo[ghi]perylenes and coronenes are presented. Irradiation with light leads to an electrocyclic reaction of the newly formed triazole ring(s) with the neighbouring bay-positions of the perylene core and after oxidation by air, the benzo[ghi]perylenes and coronenes are obtained. By using Newkome dendrimers as substituents for perylene diimides (PDIs), water solubility can be achieved after removal of the tert-butyl protecting groups. The aggregation and optical properties of the bay-functionalised PDIs, benzo[ghi]perylenes and coronenes are investigated by absorption and fluorescence spectroscopy.     

Effects of cluster formation on spectra of benzo[a]pyrene and benzo[e]pyrene

Absorption and fluorescence emission spectra of the polycyclic aromatic hydrocarbons benzo[a]pyrene (BaP) and benzo[e]pyrene (BeP) in solution and adsorbed on silica have been obtained and compared to examine the spectroscopic effects of clustering. Molecular mechanics calculations with the UFF potential were done to optimize monomer, dimer and trimer geometries, and energy differences were determined by MP2/6-31G* calculations. Fluorescence emission spectra of adsorbed BeP and BaP display a red shift that progresses with increased loading, and the two differ in their photodegradation kinetics. The experimental and theoretical results are found to be consistent.     

Fluorimetric detection of Mg2+ and DNA with 9-(alkoxyphenyl)benzo[b]quinolizinium derivatives

A benzo[b]quinolizinium-benzo-15-crown-5 ether conjugate 2a is presented that enables the fluorimetric detection of Mg(2+) and DNA by a significant light-up effect, along with a change of the emission wavelength with different analytes (Mg(2+): 495 nm; DNA: 550 nm). The mechanism of the excited-state deactivation of 2a was investigated by steady-state fluorescence spectroscopy in media of varied viscosity and compared with the photophysical properties of methoxyphenyl-substituted benzo[b]quinolizinium 2b (m,p-diOMe), 2c (m-OMe), and 2d (p-OMe) as reference compounds. Compounds 2a-c, which share the m-alkoxyphenyl substituent as the common feature, have low emission quantum yields (Φ(F) < 10(-2) in water) but exhibit a significant increase of their fluorescence intensity in viscous glycerol solutions. In contrast, the viscosity of the medium does not influence the emission properties of the parent phenyl-substituted benzo[b]quinolizinium 2e and of the p-methoxyphenyl-substituted derivative 2d. Based on these observations it is concluded that the excited-state deactivation in 2a-c is mainly due to the rotation of the m-alkoxy group about the C(ar)-O bond. The interaction of 2a-c with DNA or Mg(2+) ions was studied by spectrophotometric titrations and CD spectroscopy. Notably, the association of 2a or 2b with DNA or 2a with Mg(2+) ions induces a strong fluorescence enhancement (15- and 40-fold for DNA, 450-fold for Mg(2+)), which is rationalized by the suppression of the torsional-relaxation of the alkoxy-substituent in the excited state. Additionally, the cation-induced light-up effect of 2a is selective towards Mg(2+) ions as compared with other cations such as NH(4)(+), Li(+), Na(+), K(+) and Ba(2+).     

Fluorescent poly(aryl ether)s containing benzo[g]phthalazine and benzo[g]isoquinoline moieties

2,3‐Bis(4‐fluorobenzoyl)naphthalene was synthesized, and poly(aryl ether)s were prepared through a reaction with various bisphenols in the solvent N,N‐dimethylacetamide in the presence of potassium carbonate. Through a reaction with hydrazine or benzylamine, the corresponding benzo[g]phthalazine or benz[g]isoquinoline was formed. The conversion into heterocyclic structures resulted in a significant straightening of the chains, and the glass‐transition temperatures, inherent viscosities, and apparent molecular weights from size exclusion chromatography were significantly increased, whereas the solubilities decreased. The diketone‐containing polymers were colorless, and the benzo[g]phthalazine‐ and benz[g]isoquinoline‐containing polymers were yellow. The diketone polymers showed strong UV absorption maxima up to 350 nm, with fluorescence emission maxima around 475 nm. The heterocyclic polymers had broad absorptions up to around 450 nm, with strong emission maxima around 550 nm. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5745–5753, 2004     

Structure and vibrational spectra of mononitrated benzo[a]pyrenes

The molecules benzo[a]pyrene (BaP) and 1-, 3-, and 6-nitrobenzo[a]pyrene (1-NBaP, 3-NBaP, 6-NBaP) are currently of significant interest due to their presence in respirable combustion exhaust particulates and their mutagenic and carcinogenic properties. Structure-function correlations as well as spectroscopic signatures for trace analysis are necessary for these benzo[a]pyrene derivatives. In this paper, detailed infrared and Raman spectroscopic data of BaP and its three mononitrated isomers are provided for the first time. By utilizing density functional theory (DFT, B3LYP method with 6-311+G basis set), the molecular geometries and the vibrational spectra are calculated. Good agreement is noted between the calculated and experimental geometry for BaP, and predictions of the vibrational data for all compounds are within approximately 5 cm-1 of the experimental data. Normal mode assignments are proposed with particular emphasis on the nitro group vibrations. The geometrical distortions of the BaP structure upon nitro group substitution and correlations between structural parameters and vibrational data as well as structure-function relationships related to the mutagenicity of this important class of polycyclic aromatic hydrocarbons are discussed.     

A novel application of nylon membranes to the luminescent determination of benzo[a]pyrene at ultra trace levels in water samples

Very simple and highly sensitive methods are presented for the determination of benzo[a]pyrene, one of the most carcinogenic polycyclic aromatic hydrocarbons (PAHs). The approaches are based on solid-phase extraction of the analyte on a nylon membrane via a syringe procedure, and its fluorescent or phosphorescent determination on the solid surface. While the native fluorescence of benzo[a]pyrene retained on a nylon surface is measured directly, room-temperature phosphorescence is induced by spotting a few microlitres of thallium(I) nitrate solution on the surface (heavy-atom effect). An enhancement of the phosphorescence signal was corroborated when the measurements were carried under a nitrogen atmosphere. The analytical figures of merit obtained under the best experimental conditions demonstrate the capability of detecting benzo[a]pyrene at a sub-parts-per-trillion (sub-ng L⁻¹) level. The potential interference from other common PAHs and also from different metal ions was studied. The feasibility of determining benzo[a]pyrene in real samples was successfully evaluated through the analysis of spiked tap, underground and mineral water samples of different origins. Recoveries obtained from spiked river waters were successfully compared with those provided by a reference method, through rigorous statistical analysis.     

Desaktivierungsverhalten von arenen und heteroarenen—XXX : Die photodimerisierung und photochemische dimerenspaltung von benzo[g]chinolin und n-methylbenzo[g]chinolinium in lösung

At high concentrations (c>l·10^-3 mol l^-1) of benzo[g]quinoline and N-mcthylbenzo[g]quinolinium a fluorescence self quenching and the formation of photodimers is observed. This photoreaction is reversible, at short range excitation (275 nm) the photodimers are broken. The quantum yields of both reactions are comparable with those of the reversible photodimerization of anthracene. The variation in the gross dimerization quantum yields at different solvents in the case of benzo[g]quinoline is not explicable by the solvent viscosity, because the S₁-life time depends on the solvent too. In this case the gross dimerization quantum yield is determined by the product k_diffτXXX^w.     

The development of solid-surface fluorescence characterization of polycyclic aromatic hydrocarbons for potential screening tests in environmental samples

This paper presents the characterization of polycyclic aromatic hydrocarbons (PAHs) in solid-surface fluorescence as the first step for obtaining new optical sensors for PAHs screening. The fluorescence properties of the EPA-PAHs (naphthalene, acenaphthene, acenaphthylene, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, benzo[k]fluoranthene, benzo[b]fluoranthene, benzo[a]pyrene, indeno [1,2,3-cd]pyrene, benzo[g,h,i]perylene and dibenzo[a,h]anthracene) on five types of solid-surfaces were evaluated. The experimental variables (pH and percentage of organic solvent in samples) were studied, obtaining different possibilities for making individual sensors for some of these PAHs and the best conditions for developing sensors for PAH screening were also studied.