UV Absorption Analysis Research Articles

The impacts of different modification techniques on the gel properties and structural characteristics of fish gelatin

Fish gelatin hydrogels are typically characterized by weak texture and poor thermal stability. To address this issue, fish gelatin (FG) was modified using κ-carrageenan (κC) and transglutaminase (TG). FG-κC, FG-TG, and FG-κC-TG gels were prepared. The results demonstrated that the particle size and textural properties of FG gels were significantly enhanced by κC and κC-TG composite modifications, and their zeta potential was reduced (P < 0.05). As opposed to that, the improvement effects of TG modification were weaker. The highest particle size and hardness, along with the lowest zeta potential, were exhibited by the FG-κC-TG0.06% gel. Additionally, the FG-κC-TG gel system possessed higher apparent viscosity and elastic storage modulus. Fluorescence spectroscopy and UV absorption analysis indicated that fluorescence intensity was reduced by all three modification methods, and the conformational structure of FG was altered to varying degrees. Microstructure, FTIR, and XRD results revealed that the number of hydrogen bonds and isopeptide bonds in the composite gel systems was increased by κC and κC-TG modifications, enhancing the stability and orderliness of the gel's helical structure, and forming larger aggregates and denser network structures. Furthermore, due to the presence of covalent cross-linking, improved thermal stability was exhibited by the modified gelatin hydrogels. This study not only provides theoretical support for enhancing the performance of fish gelatin but also facilitates the application of modified fish gelatin in improving the sensory quality and flavor characteristics of food, as well as in serving as a matrix material in the biomedical field.

UV-absorption Capacity of Selected Crude and Functionalized Lignin for Use in Sunscreens

The most commonly used commercial sunscreen agents are aromatic compounds oxybenzone and octinoxate, as they offer a wide range of protection in the UV spectrum. However, oxybenzone has the highest rate of skin irritation, while octinoxate has poor photostability. Oxybenzone is also a genotoxicant and skeletal endocrine disruptor to corals. Appropriate, less toxic and preferentially biorenewable alternatives should be recommended. Lignin, an abundant byproduct of pulp and biorefinery industries, is expected to be an effective replacement for oxybenzone and octinoxate due to its aromatic structure, which, in synergy with a wide variety of functional groups, produces the absorption of energy in the entire UV region. Additionally, lignin is a biocompatible polyphenolic with a strong radical quenching ability, i.e., anti-oxidizing potential. Therefore, it is a promising replacement for synthetic chemicals in cosmetics, sunscreen, and other applications. The UV absorption analysis of selected crude and functionalized lignin samples was conducted, and the results were compared to those of commercially used UV-absorption agents—oxybenzone and octinoxate. The results showed that the total absorption capacity of the lignin samples is lower by 6.4x and 16.3x compared to oxybenzone and octinoxate, respectively; however, it covers a wide absorption range in the UV spectrum. The lignin samples also showed good photostability and color stability, in contrast to the observed yellowing of octinoxate after 3 hours of exposure to sunlight. The UV spectra of some of the lignin samples indicate that their UV absorption capacity was enhanced by as much as 13.31% after exposure to sunlight.

Physico-chemical and antifungal studies of spun cotton thread reinforced cellulose film

This study examines cellulose films reinforced with spun cotton thread and their antifungal properties. The morphology and structure of the cellulose film are analyzed using various techniques, including X-ray Diffraction (XRD), Fourier Transform Infrared (FT-IR) Spectroscopy, Field Emission Scanning Electron Microscope (FE-SEM), Atomic Force Microscope (AFM), UV–Visible Spectroscopy (UV–Vis), Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). The XRD pattern confirms the crystalline nature of the spun cotton-reinforced cellulose film. UV absorption analysis shows activity in the UV region of the optical spectrum. The reinforced cellulose film shows a band gap of 4.7 eV by employing the Wood and Tauc equation. FTIR spectroscopy confirms the film's structural formation. Morphological analysis reveals a random distribution of numerous pore structures on the material's surface. Thermalgravimetric Analysis indicates the material's stability at elevated temperatures, suggesting versatile applications. The film also exhibits antifungal activity against Candida albicans. This research highlights the potential of reinforced cellulose film in various applications, such as food and non-food packaging, offering enhanced UV protection and strength for heavy goods transport. The study emphasizes the multifunctional properties of the material, showcasing its promising role as a polymer in various practical applications.

A methodical investigation on the growth and characterization of a third-order nonlinear optical novel co-crystal of 8-hydroxyquinolinium phthalate: X-ray, Hirshfeld surface, optical, mechanical, thermal and DFT analysis

A novel non-linear optical single crystal of 8-hydroxyquinolinium phthalate has been as-synthesised by a slow evaporation solution growth technique. Single-crystal X-ray diffraction analysis affirms that it belongs to a monoclinic crystal system. While UV–visible spectroscopy shows its optical transparency with a direct band gap of 2.80 eV, a photoluminescence study confirms a principal yellow emission at 370 nm excitation. Furthermore, the mechanical and thermal properties along with the functional groups’ study have also been laid out in this paper. Intermolecular interactions present in the crystal are ascertained from Hirshfeld surface and fingerprint plot studies. The Z-scan technique has reportedly affirmed third harmonics generation in the same. Theoretical calculations using DFT modelling further testify to the experimental observations thereby laying out the framework of the mentioned crystal in terms of its optimized geometry, molecular electrostatic potential, frontier molecular orbital, natural bond orbital and natural population analysis along with vibrational assignments and UV absorption analysis.

Nanogold-decorated reduced graphene oxide for catalytic hydrogenation of 4-nitrophenol

The current work focuses on the efficacious synthesis of Au nanoparticles (NPs) decorated on reduced graphene oxide (RGO) sheets and evaluating and comparing the catalytic efficiency of the latter with graphene oxide (GO) and reduced graphene oxide (RGO) for the hydrogenation of 4-nitrophenol (4-NP). 4-NP is one of the most hazardous and widely investigated nitro compounds. Here, we report a single-step co-reduction approach for synthesizing AuRGO using hydrazine monohydrate as a reducing agent. X-ray diffraction (XRD) patterns of prepared samples confirmed the formation of GO, RGO, and AuRGO. Raman analysis gave insight into the structure and defects of prepared samples. The various oxygen-containing moieties are identified using Fourier transform infrared (FTIR) spectra and confirmed the loss of these functional groups during the reduction of GO into RGO. UV absorption analysis is carried out and is also reinforced by the finite difference time domain (FDTD) simulation studies. X-ray photoelectron spectroscopy (XPS) analysis yielded quantitative information regarding the reduction of GO into RGO and the decoration of zerovalent Au NPs on the RGO surface. Thermogram of the prepared samples manifests the thermal stability of the samples. Field emission scanning electron microscope (FESEM) and transmission electron microscopy (TEM) images depicted the morphology of GO, RGO, and AuRGO. The catalytic efficiency of AuRGO is tested by reducing 4-nitrophenol (4-NP) in the presence of sodium borohydride. AuRGO has shown enhanced catalytic efficiency compared to GO and RGO.

Study on preparation and characterisation of pure and lithium incorporated SnS thin films for solar cell applications

A ternary transition metal sulfide was synthesized and characterized by the sonochemical approach in this study, namely a Li (Li) and tin sulfide (SnS) thin film incorporating lithium (Li). Lithium incorporated SnS thin films (Li-SnS) were synthesized by equal molar ratios used in the synthesis approach. In these prepared thin films, the crystallite size averaged 5 nm and the thin films were of good crystalline nature. Nanoparticles in the thin film samples have a uniform sphere shape, with clusters forming in a few places, as seen by FE-SEM images. The presence of Li, Sn and S was confirmed through XRF spectral analysis. From the fingerprint region of the FTIR spectra, the presence of Ni, Li, Sn and sulphur was confirmed and no other impurities were detected. The UV absorption analysis was highly indicating the enhanced photon absorption behaviour of the prepared thin film samples due to the incorporation of Li with SnS samples. The efficiencies of the solar cell fabricated with SnS, Li-SnS, were found to be 6.21 and 7.92 %. From the results it is concluded that Li-SnS thin film samples can be a potential candidate for use as an electrode in solar cell applications

Preparation and Characterization of Chinese Leek Extract Incorporated Cellulose Composite Films.

This study aimed to prepare microcrystalline cellulose (MCC) films with good mechanical properties via plasticization using a Chinese leek (CL, Allium tuberosum) extract. The microstructure, crystal structure, mechanical properties, barrier ability, and thermal properties of the films were investigated. The chemical structure analysis of CL extract showed the existence of cellulose, lignin, and low-molecular-weight substances, such as polysaccharides, pectins, and waxes, which could act as plasticizers to enhance the properties of MCC:CL biocomposite films. The results of scanning electron microscopy and atomic force microscopy analyses indicated the good compatibility between MCC and CL extract. When the volume ratio of MCC:CL was 7:3, the MCC:CL biocomposite film exhibited the best comprehensive performance in terms of water vapor permeability (2.11 × 10–10 g/m·s·Pa), elongation at break (13.2 ± 1.8%), and tensile strength (24.7 ± 2.5 MPa). The results of a UV absorption analysis demonstrated that the addition of CL extract improved the UV-shielding performance of the films. Therefore, this work not only proposes a facile method to prepare MCC films with excellent mechanical properties via plasticization using CL extract but also broadens the potential applications of MCC films in the packaging area.

Structural, magnetic, optical, and photoresponse studies of hydrothermally prepared nanocrystalline GaxFe2-xO3 (x=0.7, 1 & 1.3)

Effect of gallium content on the structural, magnetic, optical and optoelectronic properties of nanocrystalline gallium ferrite GaxFe2-xO3 (x = 0.7, 1 & 1.3) prepared via hydrothermal synthesis is reported herein. X-ray diffraction, FTIR, Raman spectroscopy, and scanning electron microscopy techniques are used to study the structural and morphological properties of the samples. The crystal structure for all of the samples is single-phase orthorhombic with a P212121 space group. The structural investigation via Rietveld refinement of XRD shows a decrease in lattice parameters and volume with increasing gallium content. The structural modifications with Ga content are also confirmed from the Raman analysis and FTIR analysis. The scanning electron microscopy indicates that the size of nanoparticles is < 150 nm for all the samples, and particle size increases with Ga content. The optical and magnetic properties of GaxFe2-xO3 is not varying monotonically with x and are distinctly different from most studied Pc21n structures of GFO samples, which indicate the influence of pressure-induced cation site disorder during hydrothermal synthesis. The composition with x = 1 shows relatively less cation disorder. UV absorption analysis proves that the band gap decreases with increasing Ga concentration. The photoluminescence lifetime and quantum yield results also demonstrate the significant variation with Ga concentrations. A relatively high fluorescence value is observed for GFO with x = 1. The thin films with x < 1 show a negative photoconductive gain, whereas those with x > 1 show a positive gain. This study suggests that hydrothermally prepared nanocrystalline gallium ferrite's structural, magnetic, optical, and photosensitivity properties can be largely tailored with Ga content. The cation site disorder also plays a significant role in modulating the magneto-optical properties of this system. The photosensitivity exhibited by the multiferroic GFO systems opens an avenue into optoelectronic applications of this material.

Tuning the optoelectronic properties of superalkali doped phosphorene

In this study, the nonlinear optical (NLO) properties of pristine phosphorene and superalkali (Li3O) doped phosphorene are estimated through the density functional theory (DFT) method to investigate the optical properties. The geometries of complexes have been optimized using the B3LYP/6-31G (d, p) level of theory. The effects of doping on phosphorene have been thoroughly explained by vertical ionization energy (VIE), interaction energies (Eint), and natural bond orbitals (NBO), Moreover, the density of states (DOS), electron density difference map (EDDM) analysis, the frontier molecular orbitals (FMO) plots are also given out to find more physical divination into the electronic communication and structure property relationship. The doping of superalkali conclusively has reduced the HOMO-LUMO energy gap of M1 3.28 eV–1.25 eV for M2 making it the n-type semiconductor. The higher values of Eint,Efm and VIE obtained for M2 has indicated that this complex has higher stability and stronger interaction between superalkalis and phosphorene. More interestingly, there has been a gradual increase in the first static hyperpolarizability (βstatic) values for M1, M2 and M3 are 115.75 au, 4118.6 au, and 659.30 au respectively. The Static second hyperpolarizability (γstatic) of the doped complexes has also been calculated from which the M2 has the highest value of 1382.5 ҳ 103 au. The TD-DFT exploration has exhibited that the doped molecules are adequately transparent in the UV region. Some selected systems are also compared with the p-NA reference molecule which is a familiar external reference molecule for NLO applications. From UV absorption analysis, it can be found that these doped complexes of phosphorene may be contemplated as a new applicant for intense ultraviolet NLO materials. Computational studies have revealed the stability of M2 and M3 making them feasible as NLO materials in optoelectronic applications.

Malabar sole (Cynoglossus macrostomus) skin as promising source of type I acid and pepsin solubilized collagens with potential bioactivity.

The online version contains supplementary material available at (10.1007/s13197-021-04996-8).

Computational study of IR, Raman, and NMR spectra of 4-methylmethcathinone drug.

Molecular electronic structure, IR, UV, and NMR spectra of the most popular cathinone, known as mephedrone or 4-methylmethcathinone (4-MMC), is studied thoroughly by quantum chemical calculation in terms of the density functional theory (DFT). Geometry optimization of 4-MMC and its hydrochloride complex is performed with the B3LYP functional, and all vibrational frequencies are analyzed in all details. On this background, the IR and Raman spectra are interpreted. The importance of low-frequency terahertz and Raman spectra is stressed for distinguishing of various MMC isomers. The UV spectrum is calculated by time-dependent DFT method which allows complete interpretation of intense absorption bands at 270 and 210nm as combinations of various ππ*, nπ*, and charge transfer excitations in amino-phenyl moieties. Very informative analysis of UV absorption and NMR spectra provides useful details on the structure-activity relationship for mephedrone molecule.

Utilizing HPLC to Analyze the Presence of Anticancerous Compounds Residing from the Isolate FM1005 (Xylaria sp.) Derived from Sinularia densa

Marine organism-based natural products derived from endophytic fungi (microorganisms that reside in internal tissues of organisms and produce secondary metabolites) have been proposed as ground-breaking due to their potential to supply novel compounds for drug discovery. This investigation into possible marine-based medical applications derived from isolated compounds entailed a process inclusive of initial antiproliferative assays, the cultivation of targeted strains, and the implementation of compound separation methods for sub-fractional study and UV absorption analysis. Fractional compound analysis was conducted using a High-Performance Liquid Chromatography (HPLC) UV detector to derive probable identifications of compounds that presented antiproliferative activity. Various strains decreased the growth of A2780S (ovarian cancer), and DU-145 (prostate cancer) cell lines to the 20% and 50% viability range, respectively, and showed a degree of activity against MCF-10A (breast cancer) cell lines. Forty-eight compounds fell into the UV absorption rate range of 195-384nm, with Benzene, Rac-BINAP, and L-Histidine being commonly identified. These compound identifications can be utilized for structural analysis, novel compound discovery, and the creation of an anticancer drug that reduces the probability of cancer resurfacing in the patient. Further investigations focusing on pharmacokinetics, the biological mechanisms behind genetically inherited cancers, and the effects of specific compounds against them, such as the potential to induce apoptosis or activate inhibitory mechanisms, need to be undertaken. This research will continue to acknowledge a crucial balance point of environmental utilization, and awareness for potential future uses in the medical field.

Development of Robust Partial Least Squares Regression Model for Spectroscopic Determination of Diclofenac Sodium in Environmental Samples

Background: Diclofenac (DCF) is an important widely used non-steroidal antiinflammatory drug. Disposal of expired formulation, excretion from administered dose, the poor performance of sewage treatment process, contributes to its frequent detection in environment. Analysis of DCF in environmental sample requires time consuming pretreatment, extraction steps. Though, UV absorption analysis of DCF is simple but spectral interference of soil organic matter is a problem. The aim of this paper is to establish appropriate partial least square chemometric model for DCF quantitation through variable selection, and validation of analytical method through multivariate figure of merit analysis. Methods: Spectral data of DCF spiked soil solution is recorded and variants of partial least squares (PLS) regression viz., backward-interval PLS (biPLS), synergy-interval PLS (siPLS) and genetic algorithm (GA) based PLS models (GA-PLS) are developed from autoscaled and 2nd order differential spectrum. Prediction fidelity of the selected models was evaluated from a blind-folded semi-synthetic spectral data. The method was validated through figures of merit estimates, such as selectivity, analytical sensitivity, limits of detection and quantitation. Results: The siPLS model developed offered the minimum root mean square error of crossvalidation (RMSECV) of 0.1896 mg/l and 0.1910 mg/l for autoscaled data (9 variables) and derivative spectra (12 variables), respectively. Refinement of the derivative spectrum with GA offered a simplified model (RMSECV:0.1712, 10 variable). Conclusion: The GA based variable selection for PLS regression analysis offers robust analytical tool for DCF in environmental samples. Further research is warranted to model variable interference in spectral data unknown to analyst in priori.

Fluorescence Spectroscopy Applied to Monitoring Biodiesel Degradation: Correlation with Acid Value and UV Absorption Analyses.

The techniques used to monitor the quality of the biodiesel are intensely discussed in the literature, partly because of the different oil sources and their intrinsic physicochemical characteristics. This study aimed to monitor the thermal degradation of the fatty acid methyl esters of Sesamum indicum L. and Raphanus sativus L. biodiesels (SILB and RSLB, resp.). The results showed that both biodiesels present a high content of unsaturated fatty acids, ∼84% (SILB) and ∼90% (RSLB). The SILB had a high content of polyunsaturated linoleic fatty acid (18 : 2), about 49%, and the oleic monounsaturated (18 : 1), ∼34%. On the other hand, RSLB presented a considerable content of linolenic fatty acid (18 : 3), ∼11%. The biodiesel samples were thermal degraded at 110°C for 48 hours, and acid value, UV absorption, and fluorescence spectroscopy analysis were carried out. The results revealed that both absorption and fluorescence presented a correlation with acid value as a function of degradation time by monitoring absorptions at 232 and 270 nm as well as the emission at 424 nm. Although the obtained correlation is not completely linear, a direct correlation was observed in both cases, revealing that both properties can be potentially used for monitoring the biodiesel degradation.

PH-Dependence of the thermal stability of metallo-DNA duplexes containing ligand-type 5-hydroxyuracil nucleobases

Development of a metal-mediated base paring system has expanded the functions of DNA-based materials. We have recently reported that a 5-hydroyxuracil (UOH) nucleobase forms both a metal-mediated self-base pair (UOH–M–UOH; M=Gd(III) etc.) and a Watson–Crick-type hydrogen-bonded base pair with adenine nucleobase (UOH–A). In this study, we have investigated the pH-dependence of the thermal stability of DNA duplexes containing UOH–M–UOH base pairs or UOH–A base pairs in the absence or presence of Gd(III) or Zn(II) ions. Melting experiments and UV absorption analyses revealed that the complexation of UOH bases with Zn(II) ions altered the thermal stability of the DNA duplexes in a pH-dependent manner. In the presence of Zn(II) ions, a UOH–UOH-containing duplex was stabilized at higher pH while a UOH–A-containing duplex was destabilized. This pH-dependence of the metallo-DNA structures containing UOH nucleobases is specific to Zn(II) ions. Such dual responsiveness to both pH and metal ions would enrich switchable functions of metallo-DNA-based materials.

In vitro DNA binding studies of antiretroviral drug nelfinavir using ethidium bromide as fluorescence probe

Understanding the interaction of small molecules with DNA has become an active research area at the interface between biology and chemistry. In the present work, we investigated the mode of interaction of nelfinavir (NFV) with herring sperm DNA (hs DNA) under physiological conditions using various biophysical techniques. Analysis of UV-absorption and fluorescence spectra indicates the formation of complex between NFV and hs DNA. According to the fluorescence results, the binding constant (K) between NFV and hs DNA was found to be 3.30×104LM−1. The calculated thermodynamic parameters (ΔH° and ΔS°) suggested that hydrogen bonding plays a major role in binding between them. Phosphate group binding studies revealed that there was no electrostatic interactions occurred between NFV and hs DNA. Circular dichroism (CD) and DNA melting curve were employed to measure the conformational change of hs DNA in the presence of NFV, which verified the minor groove binding mode. These results were further supported by viscosity measurements and competitive displacement assay study using Hoechst 33258. According to the sequence specificity experiments, NFV binds to A–T rich region of hs DNA.

Formulation and in Vitro Evaluation of Self-microemulsifying Drug Delivery System Containing Fixed-Dose Combination of Atorvastatin and Ezetimibe.

This paper focuses on the development and physicochemical characterization of a self-microemulsifying drug delivery system (SMEDDS) containing a fixed-dose combination of atorvastatin (ATR) and ezetimibe (EZT). The solubility of both drugs was determined in excipient screening studies. Ternary-phase diagrams were drawn for 27 systems composed of different surfactants, cosurfactants, and oils at different surfactant-to-cosurfactant (S/CoS) ratios, and the system exhibiting the largest percentage area of the self-microemulsifying region was selected. The optimum oil ratio in the SMEDDS was selected by evaluating the mean droplet size of the resultant microemulsions. The underlying mechanism of the lower ATR loading capacity compared with EZT was elucidated by measurement of the zeta potential and UV absorption analysis. The results implied that ATR was located exclusively in the surfactant-cosurfactant layer, whereas EZT was located both in the microemulsion core and the surfactant-cosurfactant layer. In vitro dissolution studies showed that the SMEDDS had higher initial dissolution rates for both drugs when compared with marketed products. More importantly, EZT had a significantly increased dissolution profile in distilled water and pH 4.0 acetate buffer, implying enhanced bioavailability.

Design and Synthesis of High Performance Multifunctional Ultrathin Hematite Nanoribbons

1D porous ultrathin nanoribbons of hematite (α-Fe2O3) were prepared by controlled annealing of different oxides and hydroxides of iron obtained from a solvothermal synthesis method. It is found that calcination at a temperature of 500 °C for 150 min decomposes these iron hydroxides into their most stable oxide form, i.e., α-Fe2O3. Driven by different attractive forces, these porous α-Fe2O3 nanoparticles get aggregated in an ordered fashion to form an ultrathin 1D nanoribbon structure, as observed by detailed time dependent TEM and HRTEM analysis. It has been found that the high aspect ratio and porous surface morphology of these nanoribbons have significantly improved their electronic and spintronic properties as manifested by their photocatalysis, gas sensing, electrochemical, and magnetic behaviors. These hematite nanoribbons exhibit a weak ferromagnetic behavior due to surface spin disorder and shape anisotropy. Lateral confinement of electrons increases the band gap of the nanoribbons, as evident from the UV absorption analysis, which in turn improves their photocatalytic degradation efficiency (rate constant ∼0.95 h(-1)) by delaying the electron-hole recombination process. However, their liquid petroleum gas sensing properties have been found to be mainly governed by the improved (porous) surface of the hematite nanoribbons that provides huge interaction sites for the analyte gas. Most of all, these hematite nanoribbons show a significantly enhanced pseudocapacitive performance exhibited by their high specific capacitance of about 145 F g(-1) at a current density of 1 A g(-1), high rate capability, and also long cycle stability (nearly 96% of capacity retention after 1600 charging/discharging cycles).

Analysis of annual fluctuations in the content of phenol, chlorophenols and their derivatives in chlorinated drinking waters

Chlorophenols are widely represented, toxic, and persistent environmental pollutants. In this work, we analyzed annual fluctuations in the content of phenol, guaiacol, chlorophenols, chlorocatechols, and chlorinated methoxyphenols in drinking water collected in Warsaw and Tomaszów Mazowiecki (Poland). Moreover, the effect of dissolved organic matter content on the occurrence of phenolic compounds in drinking water was studied. The compounds were adsorbed on octadecyl C18 solid-phase discs, separated by the use of gas chromatography, and analyzed using mass spectrometry. The content of organic matter was evaluated by the analysis of UV absorption at 254nm by water samples. In Warsaw, raw water (derived from infiltration intakes situated in the Vistula River) and treated water (subjected to coagulation, filtration, and disinfection with chlorine dioxide) were collected in order to analyze phenols. In Tomaszów Mazowiecki, raw water (taken directly form the river) and treated water (subjected to coagulation, sand filtration, ozonation, and disinfection with gaseous chlorine) were taken to determine phenolic substances. The obtained results showed the occurrence of phenol, guaiacol, 2,4,6-trichlorophenol (2,4,6-TCP), tetrachlorophenol (TeCP), and pentachlorophenol in drinking water of both cities. Occasionally, in the waters studied, the appearance of chloroguaiacols, 3-chlorosyringol, and some chlorocatechols were noted. It was also observed that the content of dissolved organic matter in river waters may have contributed to the formation of some phenols, e.g., phenol, guaiacol, 2,4,6-TCP, and TeCP in drinking water. Finally, it was found that there were no annual (seasonal) fluctuations in phenolic compounds contents in drinking waters examined.

Behaviour of nanoparticle (ultrafine) titanium dioxide pigments and stabilisers on the photooxidative stability of water based acrylic and isocyanate based acrylic coatings

A series of nano-particle grade anatase and rutile titanium dioxide pigments have been prepared with various densities of surface treatments, particle size and surface area. Their photochemical activites have been determined and compared in water based acrylic and isocyanate acrylic coatings with typical benzophenone and hindered piperidine light stabilisers. Their performance on wood and aluminium substrates is assessed by FTIR, colour and gloss change and mass loss following artifical weathering. UV absorption analysis of benzophenone and benzotriazole chromophore based UV absorbers shows that they absorb more strongly in the near UV below 350 nm. However, nanoparticle rutile absorbs more strongly above this range and therefore, operates as a strong opacifier. Anatase also possesses opacifying behaviour, but to a lesser degree than rutile above 380 nm. In water based acrylics the absorbers undergo decomposition during irradiation whereas the nanoparticles, by virtue of their inorganic nature are inherently stable. Mass loss experiments indicated that anatase is a photosensitiser, though the intensity of the effect was found to be dependent upon the nature of the coating. Rutile was found to be an effective stabiliser with performance greater than or equal to the organic absorbers and HALS. Combinations of anatase HALS were found to be antagonistic. Little or no synergy was observed between rutile and HALS. The outstanding performance of both anatase and rutile nanoparticles is visibly and colourimetrically evident on clear acrylic wood coatings with rutile being the more effective. The 70 nm particles are more effective than the 90 nm particles. However, this data for anatase is in marked contrast to the chemical changes from FTIR analysis. Here the difference may be due to the colour bleaching effect on the lignin products through the photosensitising activity of the anatase. From a commercial point-of-view coated nanoparticles offer a significant opportunity for cost-effective benefits over conventional organic absorbers and HALS for the photoprotection of acrylic coating systems.