Dacryoliths in a series of dacryocystorhinostomies: histologic and chemical analysis.

PURPOSE: To present the clinical and intraoperative characteristics of dacryolith cases, to present their histologic and chemical analysis, and to relate the findings with the probable causes of their formation in a series of dacryocystorhinostomies performed in northern Greece. METHODS: In a series of 242 dacryocystorhinostomies in patients with chronic dacryocystitis, dacryoliths large enough to perform an accurate chemical analysis and a light histologic examination were found in five cases. The chemical analysis was based on atomic absorption spectrophotometry and atomic emission spectrometry. RESULTS: These five cases concerned relatively young patients who presented symptoms of short duration as compared to the other dacryocystorhinostomy cases. In three of them, irregularities of the lacrimal sac wall were observed. The final postoperative results were satisfactory. The histologic examination revealed acellular amorphous organic material and limited areas with characteristics of calcium salt depositions. The chemical analysis showed mainly organic and minimal inorganic material. CONCLUSIONS: The irregularities of the lacrimal sac wall and the consequent flow disorders within the sac and the histologic and chemical analysis of the dacryoliths provide evidence for etiologic consideration.

Size distribution of trace elements and polycyclic aromatic hydrocarbons in fly ashes generated in Greek lignite-fired power plants.

The fly ashes arrested by the electrostatic precipitators of four large lignite-fired Greek power stations (total installed capacity 4048 MW) were investigated regarding the distribution of 27 major, minor and trace elements and 13 polycyclic aromatic hydrocarbons (PAHs) in six size ranges from <40 to >105 microm. An inverse relationship of concentration with particle size was observed for trace elements, such as As, Se, Zn, Pb, Cd, as well as for Ca, whereas the distribution of the matrix elements Al, Si, Ti, Fe, Mg was fairly flat up to 105 microm with relative enrichment or depletion in larger particle sizes. A reverse relationship of concentration with particle size was also revealed for all PAHs, particularly the heavier compounds. The percent mass of all elements and PAH species in the suspendable fraction (<63 microm) was between 25 and 30%. In all fly ashes, the PAH mixture was dominated by 4-ring species (48-62%) followed by 3-ring compounds (38-41%), whereas the carcinogenic 5- and 6-ring PAHs were less abundant (2-11%). Fly ash PAH concentrations were found to correlate strongly with the concentrations of certain trace elements either positively (e.g. Ba) or negatively (Mg, Cr, V, U) thus suggesting that some lignite elements might promote or prevent PAH formation during combustion. The suspendable fly ash fraction (<63 microm) was found to contain 6-35% of the total mass of individual elements and 10-57% of the total mass of individual PAH components.

Assessment of the surface water quality in Northern Greece.

The application of different multivariate statistical approaches for the interpretation of a large and complex data matrix obtained during a monitoring program of surface waters in Northern Greece is presented in this study. The dataset consists of analytical results from a 3-yr survey conducted in the major river systems (Aliakmon, Axios, Gallikos, Loudias and Strymon) as well as streams, tributaries and ditches. Twenty-seven parameters have been monitored on 25 key sampling sites on monthly basis (total of 22,350 observations). The dataset was treated using cluster analysis (CA), principal component analysis and multiple regression analysis on principal components. CA showed four different groups of similarity between the sampling sites reflecting the different physicochemical characteristics and pollution levels of the studied water systems. Six latent factors were identified as responsible for the data structure explaining 90% of the total variance of the dataset and are conditionally named organic, nutrient, physicochemical, weathering, soil-leaching and toxic-anthropogenic factors. A multivariate receptor model was also applied for source apportionment estimating the contribution of identified sources to the concentration of the physicochemical parameters. This study presents the necessity and usefulness of multivariate statistical assessment of large and complex databases in order to get better information about the quality of surface water, the design of sampling and analytical protocols and the effective pollution control/management of the surface waters.

Vitrification of lead-rich solid ashes from incineration of hazardous industrial wastes.

Lead-rich solid industrial wastes were vitrified by the addition of glass formers in various concentrations, to produce non-toxic vitreous stabilized products that can be freely disposed or used as construction materials. Toxicity of both the as-received industrial solid waste and the stabilized products was determined using standard leaching test procedures. The chemically stable vitreous products were subjected to thermal annealing in order to investigate the extent of crystal separation that could occur during cooling of large pieces of glass. Leaching tests were repeated to investigate the relation between annealing process and chemical stability. X-ray, scanning and transmission electron microscopy techniques were employed to identify the microstructure of stabilized products before and after thermal treatment. Relation between synthesis and processing, chemical stability and microstructure was investigated.

A study of bismuth-film electrodes for the detection of trace metals by anodic stripping voltammetry and their application to the determination of Pb and Zn in tapwater and human hair.

This work reports the simultaneous determination of Cd(II), Pb(II) and Zn(II) at the low mug l(-1) concentration levels by square wave anodic stripping voltammetry (SWASV) on a bismuth-film electrode (BFE) plated in situ. The metal ions and bismuth were simultaneously deposited by reduction at -1.4 V on a rotating glassy carbon disk electrode. Then, the preconcentrated metals were oxidised by scanning the potential of the electrode from -1.4 to 0 V using a square-wave waveform. The stripping current arising from the oxidation of each metal was related to the concentration of each metal in the sample. The parameters for the simultaneous determination of the three metals were investigated with the view to apply this type of voltammetric sensor to real samples containing low concentrations of metals. Using the selected conditions, the limits of detection were 0.2 mug l(-1) for Cd and for Pb and 0.7 mug l(-1) for Zn at a preconcentration time of 10 min. Finally, BFE's were successfully applied to the determination of Pb and Zn in tapwater and human hair and the results were in satisfactory statistical agreement with atomic absorption spectroscopy (AAS).

Flow-injection manifold for the simultaneous spectrophotometric determination of Fe(II) and Fe(III) using 2,2'-dipyridyl-2-pyridylhydrazone and a single-line double injection approach.

A simple and rapid flow-injection (FI) method is reported for the simultaneous spectrophotometric determination of Fe(II) and Fe(III) in pharmaceutical products. The method is based on the reaction of Fe(II) with 2,2'-dipyridyl-2-pyridylhydrazone (DPPH) in acidic medium to form a water-soluble reddish complex (lambdamax=535 nm). Fe(III) reacts with DPPH under flow conditions only after its on-line reduction by ascorbic acid (AsA). Both analytes were determined in the same run via a double-injection valve, which enabled the simultaneous injection of two sample volumes in the same carrier stream (,,single-line double-injection" approach). The two well-defined peaks produced corresponded to total iron [Fe(II)+Fe(III)] and Fe(II). Speciation of the analytes in their mixtures was achieved by multiple regression analysis. The calibration curves obtained were linear over the ranges 0-30 and 0-50 mg L(-1) for Fe(II) and Fe(II), respectively, and the precision [s(r)=1.0% for Fe(II) and 1.5% for Fe(III)] was satisfactory. The method proved to be selective and adequately sensitive (cL=0.25 and 0.17 mg L(-1) for Fe(III) and Fe(II), respectively, in mixtures). Application of the method to the analysis of pharmaceutical samples resulted in excellent accuracy; the percent mean recoveries were in the range 99.0-102.0% for both Fe(II) and Fe(III) and the mean relative error was e(r)=1.0%.

Direct and selective flow-injection method for the simultaneous spectrophotometric determination of calcium and magnesium in red and white wines using online dilution based on "Zone Sampling".

The present work reports a selective and simple flow injection method for the direct and simultaneous determination of calcium and magnesium ions in red, rose, and white wines. Both ions react with methylthymol blue (MTB) at a strongly basic medium to form colored complexes that are monitored spectrophotometrically (lambda(max) = 610 nm). The simultaneous determination is achieved by online masking of magnesium by 8-hydroxyquinoline (8-HQ). Incorporating an online dilution mode based on the "zone sampling" technique in the FI system, the determination of both analytes was achieved without any pretreatment of the samples, in the range 0-350 mg L(-1) and 0-200 mg L(-1) for Ca(II) and Mg(II), respectively. The 3 sigma detection limits were quite satisfactory (2.1 and 1.8 mg L(-1) for Ca(II) and Mg(II) respectively), and the precision was 1.2% (at a mixture of 100.0 mg L(-1) Ca(II) + 100.0 mg L(-1) Mg(II), n = 12). A detailed study of interferences proved that the proposed method is highly selective. The application of the method to the direct analysis of red, rose, and white wines yielded excellent results compared with those obtained by using FAAS as a reference method (e(r) < 2.8%).

Dacryoliths in chronic dacryocystitis and their composition (spectrophotometric analysis).

PURPOSE: To present the findings from histological and chemical analysis of large dacryoliths and correlate them with previous reports. MATERIALS AND METHODS: Dacryoliths were found in 8% of 216 dacryocystorhinostomy operations. In two cases with mild chronic dacryocystitis, large dacryoliths were extracted. The first case was a 42-year-old male with three dacryoliths in a lacrimal sac, presenting diverticulum-like formations, the second was a 22-year-old woman with one dacryolith at the entrance of the nasolacrimal duct. Chemical analysis was based on atomic absorption spectrophotometry (F.AAS) and on atomic emission spectrometry (AES). Light histological examination was also done. RESULTS/CONCLUSIONS: The findings were the same in both cases. Histological examination revealed amorphous organic material, and limited areas with the characteristics of calcium salt depositions. Chemical analysis showed mainly organic material with only minimal inorganic material. Explanations are offered about the formation of these dacryoliths.