Multiresidue analytical method for the determination of antimicrobials, preservatives, benzotriazole UV stabilizers, flame retardants and plasticizers in fish using ultra high performance liquid chromatography coupled with tandem mass spectrometry

A multiresidue analytical method for the determination of emerging pollutants belonging to personal care products (PCPs) (antimicrobials, preservatives), benzotriazole UV stabilizers (BUVSs) and organophosphorus compounds (OPCs) in fish has been developed using high speed solvent extraction (HSSE) followed by silica gel clean up and ultra fast liquid chromatography coupled with tandem mass spectrometry (UFLC–MS/MS) analysis. Developed extraction and clean up method yielded good recovery (>70%) for all the four groups of emerging pollutants, i.e. antimicrobials (78.5–85.6%), preservatives (85.0–89.4%), BUVSs (70.9–112%) and OPCs (81.6–114%; except for TEP – 68.9% and TPeP – 58.1%) with RSDs ranging from 0.7 to 15.4%. Intra- and inter-day repeatabilities were less than 19.8% and 19.0%, respectively at three spiked levels. The concentrations were given in lipid weight (lw) basis, and the method detection limits were achieved in the lowest range of 0.001–0.006 ng g⁻¹ for two antimicrobials, 0.001–0.015 ng g⁻¹ for four preservatives, 0.0002–0.009 ng g⁻¹ for eight BUVSs and 0.001–0.014 ng g⁻¹ for nine OPCs. Finally, the method was successfully validated as a simple and fast extraction method for the determination of 23 compounds belonging to PCPs, BUVSs and OPCs and applied to the analysis of three species of fish from Manila Bay, the Philippines. Concentrations ranged from 27 to 278 ng g⁻¹ for antimicrobials, 6.61 to 1580 ng g⁻¹ for paraben preservatives, −1 for BUVSs and ND (not detected) to 266 ng g⁻¹ for OPCs suggesting the ubiquitous contamination by these emerging pollutants in Manila Bay. This is the first method developed for the determination of triclocarban, four paraben preservatives and four BUVSs, in fish.     

Effect of Flux on thermoluminescence in Flux-grown BaFCl crystals

BaFCl crystals have been grown using BaF₂ and BaCl₂ by flux technique. Glow curves, optical absorption, and TL emission spectra of x/r — irradiated crystals are studied. The results have been compared with those BaFCl crystals grown from NaF flux so as to study the effects of flux on these properties. It is found that crystals grown from BaF₂ flux are relatively purer. An additional TL glow peak at 460 K, an optical absorption band at 775 nm and TL emission band at 485 nm have been obtained in the presently grown crystals. The additional glow peak, optical absorption band have been attributed to F(¯F) aggregate centers, whereas the 485 nm TL emission band to impurity centers.     

Dielectric and electrical studies on Samarium Oxide thin film capacitors

Sm₂O₃ films were prepared by thermal evaporation using tantalum boats. Current-voltage characteristics were drawn for different film thicknesses. The breakdown voltage and dielectric strengths were calcualted for different film thicknesses and the applicability of Forlani-Minnaja relation was discussed. The effect of dc voltage on capacitance and tan δ was studied. The results were explained on the basis of Schottky barriers existing at metalinsulator interface which are due to the presence of oxygen vacancies. The presence of oxygen vacancies were established from thermoluminescence studies. The effect of ac voltage on capacitance and tan δ were also studied and the results were discussed.     

Glow curves and the emission of BaFCl:Eu2+

Thermoluminescence and the emission of γ-irradiated BaFCl:Eu²⁺ has been studied. A well defined glow peak at 400 K and a shoulder at 480 K are obtained in addition to those obtained as in undoped BaFCl. Thermoluminescence emission has shown a band at about 390 ∼ 400 nm. Additional glow peaks have been attributed to the luminescence centers as caused by europium impurity.     

Dielectric properties of vacuum deposited Samarium Oxide sandwich structures

Samarium oxide films were prepared by vacuum thermal evaporation using tantalum boats. The effect of aging, frequency and annealing on capacitance and tan δ were studied for Al Sm₂O₃ Al capacitor structures. The variation in capacitance with frequency at low frequency region is quite considerable. The existence of oxygen vacancies were confirmed from the thermoluminescence studies of these oxide films. The results were discussed on the basis of oxygen vacancies existing in these films.     

Radiation hardening studies in KBr-KI mixed crystals

Radiation hardening studies have been made in KBr, KI and in different compositions of KBr-KI mixed crystals, grown from melt by Kyropoulos technique. The irradiation hardness in mixed crystals is found to vary non-linearly with composition, attaining a minimum value at intermediate compositions. Dislocation density measurements have shown a high concentration of dislocations and grain boundaries in mixed crystals as compared to end crystals. The results obtained on radiation hardening of mixed crystals were explained in terms of dislocations present in them.     

A study of Z1-centers in γ-irradiated KCl:Ba2+ crystals

The purpose of the paper is to report the optical absorption and thermoluminescence measurements on KCl: Ba²⁺ crystal irradiated with γ-rays. Bleaching in F-band increases the glow peak around 75 °C and suppresses the 125 °C peak. A similar result is observed in preheat treated crystals. When this peak is thermally cleaned, the broadening of the absorption on the prolonged F-bleached crystals is removed. On the basis of these observations, the glow peak at 75 °C is tentatively attributed to Z₁-centers.