Fluorescent Whitening Agents Research Articles

A One-Pot Route to 3-Vinyl Coumarins

Coumarins are one of the most widely used classes of fluorescent dyes and have found applications in organic light-emitting diodes, optical brighteners, and fluorescent labels. The authors present a convenient one-pot synthesis of 3-vinylcoumarins 3. The π-electron system can be further extended by Heck coupling with aryl halides leading to a variety of substituted coumarin dyes 4.

Fundamental study for quantitative analysis of the fluorescent whitening agent (FWA) content of paper and process water

Fluorescent whitening agents (FWAs) are the most widely used functional chemicals for the manufacture of printing and writing grades of paper. FWAs are used as internal or external additives for the surface treatment on the size press and coater. In spite of the extensive use of FWAs, no method has been established to analyze the FWA content in process water and paper products. Samples are typically exposed to UV light in order to detect the presence of FWAs. This method is based on the fluorescence exhibited by FWAs under a UV-lamp. The observation of fluorescence with the naked eye is highly subjective. Thus, it is essential to develop a more scientific and objective to the quantitative analysis of FWA optical effects. Water and paper samples containing FWAs were prepared in a laboratory. Quantitative analysis was carried out with a spectrofluorometer, a spectrophotometer, and an image restoration microscope. Using these analytical instruments, fluorescence was observed. Regression equations were obtained from the relationship between the fluorescence intensity and the FWA optical effects of the samples.

The discrimination potential of diffuse-reflectance ultraviolet–visible–near infrared spectrophotometry for the forensic analysis of paper

The application of diffuse reflectance UV-VIS-NIR spectroscopy is proposed to differentiate 20 office paper samples, which had been deemed similar by a preliminary visual examination under several different lighting sources. The samples were firstly screened on the basis of the qualitative appearance of their spectra. A further discrimination was obtained by taking into account three parameters: the average reflectivity of the paper samples in the range 680-900nm, and the integrated intensity of the absorption peak in the UV range at 272nm and at 360nm. The homogeneity of these parameters on both sides of the paper sheets was assessed, detecting a very uniform distribution of the optical brighteners. A special focus was posed on the determination of the discriminative power, in order to give a quantitative parameter on the proposed procedure, which is important when reporting results to the Court. The remarkable achievement of differentiating all the examined samples was obtained by UV-VIS spectroscopy, a very less expensive technique which is readily available in practically all forensic laboratories.

Analysis of a naturally-occurring deletion mutant of Spodoptera frugiperda multiple nucleopolyhedrovirus reveals sf58 as a new per os infectivity factor of lepidopteran-infecting baculoviruses

The Nicaraguan population of Spodoptera frugiperda multiple nucleopolyhedrovirus, SfMNPV-NIC, is structured as a mixture of nine genotypes (A–I). Occlusion bodies (OBs) of SfMNPV-C, -D and -G pure genotypes are incapable of oral transmission; a phenotype which in SfMNPV-C and -D is due to the absence of pif1 and pif2 genes. The complete sequence of the SfMNPV-G genome was determined to identify possible factors involved in this phenotype. Deletions of 4860bp (22,366–27,225) and 60bp (119,759–119,818) were observed in SfMNPV-G genome compared with that of the predominant complete genotype SfMNPV-B (132,954bp). However no genes homologous to previously described per os infectivity factors were located within the deleted sequences. Significant differences were detected in the nucleotide sequence in sf58 gene (unknown function) that produced changes in the amino acid sequence and the predicted secondary structure of the corresponding protein. This gene is conserved only in lepidopteran baculoviruses (alpha- and betabaculoviruses). To determine the role of sf58 in peroral infectivity a deletion mutant was constructed using bacmid technology. OBs of the deletion mutant (Sf58null) were not orally infectious for S. frugiperda larvae, whereas Sf58null rescue virus OBs recovered oral infectivity. Sf58null DNA and occlusion derived virions (ODVs) were as infective as SfMNPV bacmid DNA and ODVs in intrahemocelically infected larvae or cell culture, indicating that defects in ODV or OB morphogenesis were not involved in the loss of peroral infectivity. Addition of optical brightener or the presence of the orally infectious SfMNPV-B OBs in mixtures with SfMNPV-G OBs did not recover Sf58null OB infectivity. According to these results sf58 is a new per os infectivity factor present only in lepidopteran baculoviruses.

Synthesis and Properties of New Anionic Fluorescent Brighteners

Three new fluorescent brighteners (FBs) were synthesized and compared with traditional FBs. Their UV/visible absorption and fluorescence emission characteristics were studied. Compared with traditional products, the new fluorescent brighteners had better optical performance, high solution and low pollution.

Limitations in the efficiency of fluorescent whitening agents in uncoated paper

The fluorescence efficiency of one fluorescent whitening agent (FWA) inuncoated and unfilled paper was characterised at different FWA concentrations. An extendedKubelka-Munk model proposed earlier ...

Practical method for measuring printed colors on FWA-treated paper

The virtual fluorescent standard (VFS) method is a new approximation method for the practical measurement of the colorimetric properties of an object treated with fluorescent whitening agent (FWA). The essential requirement of the VFS method is that the bi-spectral characteristics of the VFS must be similar in curve shape to those of the object to be measured. In the case of an object printed on an FWA-treated substrate, the bi-spectral characteristics will vary depending on not only the substrate but also the printed ink films. In this study, two simplified VFS methods, one using the bi-spectral characteristics of the substrate and the other using those of typical paper as the VFS instead of those similar to each object, were evaluated. The evaluation was performed using two instrument models for the VFS method with the different illuminations with five sets of 13 samples printed in different colors by five different printer/paper combinations. In this evaluation, the total spectral radiance factor of each sample was obtained by simulated measurement, that is, it was calculated based on the bi-spectral radiance factor of the sample and the spectral power distributions of the light source of the instrument. The total spectral radiance factor of each sample under D50 obtained using both VFS models and CIE L*a*b* values derived therefrom were compared with those by the reference model with ideal D50 illumination. Although the samples are limited, the results shows that both simplified VFS methods remarkably reduce the errors due to fluorescence when compared to the conventional method. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2012

Synthesis of novel stilbene-alkoxysilane fluorescent brighteners, and their performance on cotton fiber as fluorescent brightening and ultraviolet absorbing agents

Two novel fluorescent brightening agents (compounds 3a–b shown in Figure 1) were synthesized, using a facile three-step synthetic route, from 4,4′-diamino-2,2′-disulfonic-stilbene, cyanuric chloride, and a readily cross-linkable 3-aminopropyltrimethoxy silane. The products contain hydrolytically active trimethoxysilyl, (–Si(OCH) 3), functional groups that readily hydrolyze in the presence of water, and subsequently generate a water insoluble silicon cross-linked-network (Si–O–Si) via a condensation process. The cross-linked product hydrolyzes on treatment with hot aqueous sodium hydroxide to silanols (–Si(OH) 3) to form compounds 4a–b which are readily water soluble and produce a clear fluorescent solution. The silanol forms of compounds 4a–b were used for further characterization and performance evaluation. The structures of compounds 4a–b were characterized by 1H-NMR, Fourier -Transform infrared (FT-IR) spectroscopy and negative electrospray ionization mass ( −ESI-MS) spectroscopy. Compounds were applied to cotton fiber as fluorescent brightening agents and their performance was evaluated by measuring the degree of whiteness, ultraviolet protection factor (UPF), fluorescence and acid fastness. Results showed that application of 0.25% (o.w.f) of compounds 4a–b impart a high degree of whiteness (CIE WI = 144, 139) as well as good ultraviolet protection factor (UPF = 29, 27) on cotton fiber exhibiting a significant increase in whiteness and UV blocking properties compared to untreated substrate (CIE WI = 81, UPF = 5). Acid fastness tests of both compounds showed a slight change in fluorescence emission intensities as a function of pH. In acidic solutions, a shift in emission maximum occurs at pH 3 from 434 to 453 nm and from 435 to 457 nm, due to the protonation of amino and sulfonic groups of stilbene fluorophore which substantially reduces the quenching process.

Determination of quantum efficiency in fluorescing turbid media

A method is proposed to estimate the optical parameters in a fluorescing turbid medium with strong absorption for which traditional Kubelka-Munk theory is not applicable, using a model for the radiative properties of optically thick fluorescent turbid media of finite thickness proposed in 2009 [J. Opt. Soc. Am. A26, 1896 (2009)]. The method is successfully applied to uncoated papers with different thicknesses. It is found that the quantum efficiency of fluorescent whitening agents (FWAs) is nearly independent of the fiber type, FWA type, FWA concentration, and filler additive concentration used in this study. The results enable an estimation of the model parameters as function of the FWA concentration and substrate composition. This is necessary in order to use the model for optimizing fluorescence in the paper and textile industries.

A Portable, Low-Cost, LED Fluorimeter for Middle School, High School, and Undergraduate Chemistry Labs

A low-cost portable fluorimeter was constructed using a 360 nm LED for excitation and a silicon photodiode for detection. The instrument is simple to operate and has been used to investigate fluorescent whitening agents extracted from various brands of paper, to determine the linear range and limit of detection of quinine in various commercial tonic water samples, and to quantify the amount of vitamin B1 in commercial multivitamin supplements. The instrument is straightforward to construct and to use and facilitates the introduction and hands-on application of spectroscopy, fluorescence, and related topics in middle school, high school, and undergraduate laboratory courses.

Synthesis and fluorescent investigations of VBL-based waterborne polyurethane dye

Fluorescent brightening agent VBL-based waterborne polyurethane dye (VBL–WPU) was synthesized by incorporation of VBL into waterborne polyurethane chains. The expected structure of polymeric fluorescent brightening agent was confirmed by FT-IR and UV–vis spectra. The molecular weight, average particle sizes and the contents of VBL segments in VBL–WPU were investigated. This polymeric dye exhibited intriguing optical behaviors. The absorption and emission maxima of VBL–WPU showed obviously hypsochromic shift in comparison with those of VBL. The fluorescence intensity of the polymer was prominently enhanced comparing with VBL because of the changes of micro-circumstance of VBL. Furthermore, the fluorescence of VBL–WPU was not sensitive to hydroquinone quencher.

Synthesis and characterization of a novel waterborne stilbene-based polyurethane fluorescent brightener

Abstract A novel waterborne stilbene-based polyurethane fluorescent brightener dispersion WPU-VBL was synthesized by incorporating chemically disodium 4,4′-bis[(4-anilino-6-hydroxyethylamino-1,3,5-triazin-2-yl)amino]stilbene-2,2′-disulphonate (VBL) into the polyurethane chain using isophorone diisocyanate, poly(propylene glycol) and 2,2-dimethylol propionic acid. The structure of WPU-VBL was confirmed by means of Fourier transform infrared spectroscopy. The UV–vis absorption analysis showed a hypsochromic shift of 16 nm when VBL was blocked into polyurethane chain. Number average molecular weight of 2.1 × 10 4 , molecular weight distribution of 2.1 and average latex particle size of about 70 nm for WPU-VBL were determined based on the analysis of gel permeation chromatography and laser particle size analyzer. It was found that the fluorescence intensity of WPU-VBL was prominently enhanced because of the micro-circumstance of VBL and the fluorescence of WPU-VBL was very stable.

Evaluation of microbiological water quality in the Pettaquamscutt River (Rhode Island, USA) using chemical, molecular and culture-dependent methods

We evaluated microbiological water quality in the Pettaquamscutt River (Rhode Island, USA), an estuarine river. Fecal coliform (FC) and enterococci (FE) bacteria, presence of Bifidobacterium adolescentis DNA (indicating human fecal contamination), and optical brightener (OB) fluorescence (associated with laundry detergents) were determined for 14 stations from May to September 2010. Six stations had high counts of FE and FC, and the presence of B. adolescentis DNA and high OB fluorescence indicated human fecal contamination – four had septic systems as likely sources of contamination; the others were in sewered areas. The ability of FC and FE to indicate human fecal contamination was assessed against a positive B. adolescentis test. FC and FE had false positive rates of 25% and 17%, respectively, and false negatives of 44% for FC and 63% for FE. Inclusion of molecular and chemical indicators should improve tracking of human fecal contamination sources in the river.

Effect of fluorescent whitening agent on the transcription of cell damage‐related genes in zebrafish embryos

7-Diethylamino-4-methylcoumarin (DEMC) is a fluorescent whitening agent (FWAs). There have been some studies on DEMC's protective effects against biological activity but there are few papers about the in vivo toxicity of DEMC. In this study, we used wild-type zebrafish embryos 3 days post fertilization (dpf). Test solutions with DEMC concentrations were negative control (without vehicle), 0 (with vehicle, 0.01% v/v ethanol), 0.25, 0.5, 0.75, 1.0, 1.25, 1.5 and 2 ppm. Embryos and larvae were counted for survival rate and hatching rate. Heart rates were also counted at 2.5 and 3.0 dpf. At 3.0 dpf, quantitative RT-PCR was performed with some samples (0, 0.25, 0.75 and 1.25 ppm) to determine the toxic effect to DEMC by detecting the expression levels of toxic-responsive genes. We used 11 genes, which included oxidative stress-related genes [sod(Mn), sod(Cu,Zn) and hsp70], mitochondrial metabolism-related genes (coxI, pyc, cyt and cyclinG1) and apoptosis-related genes (c-jun, bcl2, bax and p53). High-concentration DEMC-treated groups showed significant different survival rate, hatching rate and heart rate compared with low-concentration DEMC-treated groups. The LC50 of this chemical, 0.959 ppm, was calculated. We also confirmed that some genes in the DEMC exposure groups showed significantly up-regulations in expression levels compared with control groups. We concluded that the fluorescence agent, DEMC, has possible developmental toxicities and alteration effect of gene expression, which are related to oxidative stress, mitochondrial metabolism and apoptosis in zebrafish embryos.

Synthesis and Photoproperties of Fluorescent Brighteners Modified by Polyaminamide

One of amino compounds of traditional fluorescent brighteners with polyaminamide was replaced and new triazinyl aminostilbene fluorescent brightener was modified by polyaminamide which synthesized through three-step condensation reaction. The molecular structures were characterized by IR spectrum and photoproperties in aqueous and ethanol were studied by ultraviolet absorption spectra, fluorescence emission spectra, photochemical stability and paper coating application test. The results show that the light stability and fluorescence quantum yield of polyaminamide fluorescent brighteners (PFBs) were improved obviously, which compared with the traditional FBs, such as VBL, and the whitening performance of paper coating enhanced and used widely. Meanwhile, the photophysics and photochemical properties of triazene-stilbene fluorescence brighteners are markedly determined by solvent polarity.

Determination of residual <I>N,N</I>-dimethylformamide in fluorescent brightening agent CBS by reversed-phase high performance liquid chromatography

A method for the determination of N,N-dimethylformamide (DMF) residue in fluorescent brightening agent CBS by reversed-phase high performance liquid chromatography (RP-HPLC) was established. An Ameritech Accurasil C18 column (150 mm x 4.6 mm, 5 microm) was used with methanol-water as the mobile phase with gradient elution. The flow rate of the mobile phase was 1.0 mL/min and the detection wavelength was 205 nm. The column temperature was 30 degrees C and the injection volume was 5 microL. There was a good linear relationship between the peak area and the concentration of DMF in the range of 0.19 - 141 mg/L. The recoveries of DMF were 98.4% - 107.3% at the spiked levels of 0.2344% and 0.4678%. The limit of detection was 0.019%. The relative standard deviation was 1.73%. This method can be used for the determination of DMF in fluorescent brightening agent CBS quickly and accurately.

Colour responsive smart polymers and biopolymers films through nanodispersion of organic chromophores and metal particles

Molecular optical brighteners incorporated into filmable polymers to a very low extent from 0.05 to 0.5 wt.% by melt-processing, provide materials which show a well-defined excimer emission by increasing dye concentration flanked by a characteristic change of the luminescent properties of the films. Then, the original colour of the film, provided by the radiative transitions of the isolated dye molecules, may be restored after polymer stretching that promotes the aggregates break-up and the alignment of the single chromophore molecules along the stretching direction thus providing an easy detectable colour change. The approach can be extended to polymer blends allowing to obtain a wide range of films with different structure and performances in colour changes determined by external stimuli. Also, nanostructured polymer films with unusual and anisotropic optical properties can be obtained through the dispersion of gold and silver nanoparticles. The metal nanoparticles can be produced directly inside the polymer matrix by a photo-reduction process. Both organic chromophores and metal particles nanostructured systems can be used to prepare “smart” coating materials with a broad type of structural characteristics and capable to detect and stores external stimuli of different origin and under different conditions.

Możliwości wykorzystania mikroskopii fluorescencyjnej UV do badania rozmieszczenia impregnatów wzmacniających w nasycanym drewnie na tle metod dotychczas stosowanych

The paper describes methods of the analysis of the extent of impregnation of historic wood with strengthening consolidants. The authors propose including the method UV-fluorescence microscopy combined with the utilisation of fluorescent markers of the applied solutions to the workshop of researchers working in this field. The reader is introduced with the basics of UV-fluorescence microscopy and the chemical nature of fluorescent markers. The test were conducted on non-painted wood and wood covered with layers of priming and paint. The solutions of Paraloid B-72 in toluene, 1-metoksy-2-propanol and dipropylene glycol methyl ether. As markers an addition of fluorescent violet (or the Lumogen dyes group) and fluorescent brighteners PER and 4BCextra (Stilbene derivatives) were used. The proposed method met the requirements, allowing for determination of resin distribution in wood, the penetration paths of the impregnate as well as for estimation of the extent of saturation of polychrome layers, at the same time permitting photographic documentation of test results.

Metal enhanced fluorescence of the fluorescent brightening agent Tinopal-CBX near silver island film

Metal-enhanced fluorescence (MEF) studies of the optical brightener Tinopal-CBS (4,4′- distyrylbiphenyl sulfonic sodium salt) have been undertaken using steady-state and time resolved fluorescence measurements on silver island films (SiFs) deposited on glass slides and silver nano-particles adsorbed onto cellulose based filter paper. Nearly a 4.5 fold enhancement in fluorescence intensity is observed from both SiFs and nano-particle deposited cellulose filter paper. In addition an enhanced photostability and decrease in decay time is also observed on SiFs. These results are consistent with two distinct mechanisms of MEF, firstly coupling and transferring of the excited states energies of fluorophores to surface plasmons in the silver island deposited glass films, and secondly, an electric field enhancement effect, which facilitates enhanced absorption of the fluorophores. Our findings reveal significant benefits of enhanced luminescence and prolonged photostability of Tinopal CBS. As such, Plasmon-tinopal constructs offer new material opportunities as well as multifarious applications in the life sciences.

Root hair-specific disruption of cellulose and xyloglucan in AtCSLD3 mutants, and factors affecting the post-rupture resumption of mutant root hair growth

The glycosyl transferase encoded by the cellulose synthase-like gene CSLD3/KJK/RHD7 (At3g03050) is required for cell wall integrity during root hair formation in Arabidopsis thaliana but it remains unclear whether it contributes to the synthesis of cellulose or hemicellulose. We identified two new alleles, root hair-defective (rhd) 7-1 and rhd7-4, which affect the C-terminal end of the encoded protein. Like root hairs in the previously characterized kjk-2 putative null mutant, rhd7-1 and rhd7-4 hairs rupture before tip growth but, depending on the growth medium and temperature, hairs are able to survive rupture and initiate tip growth, indicating that these alleles retain some function. At 21°C, the rhd7 tip-growing root hairs continued to rupture but at 5ºC, rupture was inhibited, resulting in long, wild type-like root hairs. At both temperatures, the expression of another root hair-specific CSLD gene, CSLD2, was increased in the rhd7-4 mutant but reduced in the kjk-2 mutant, suggesting that CSLD2 expression is CSLD3-dependent, and that CSLD2 could partially compensate for CSLD3 defects to prevent rupture at 5°C. Using a fluorescent brightener (FB 28) to detect cell wall (1 → 4)-β-glucans (primarily cellulose) and CCRC-M1 antibody to detect fucosylated xyloglucans revealed a patchy distribution of both in the mutant root hair cell walls. Cell wall thickness varied, and immunogold electron microscopy indicated that xyloglucan distribution was altered throughout the root hair cell walls. These cell wall defects indicate that CSLD3 is required for the normal organization of both cellulose and xyloglucan in root hair cell walls.