Study of ancient Islamic gilded pieces combining PIXE-RBS on external microprobe with sem images

Numerous metallic objects with very aesthetic and technological qualities have been recovered by archaeological excavations. Adequate processes of restoration and conservation treatments require the accurate determination of the elemental composition and distribution within the objects, as well as the identification of the nature and distribution of the corrosion products. Ideally the identification method should cause no alteration in the sample. In this work, different archaeological pieces with a gilded look have been characterized using simultaneously PIXE and RBS at the CMAM external microprobe in order to study the gilding metalworking done in the Iberian Peninsula during the Middle Ages. The gold layer thickness and its elemental concentrations of Ag, Au and Hg were determined by both techniques and compared with the scanning electron microscopy images obtained for some fragments of pieces. PACS  29.30.Kv; 87.64.-t     

Microencapsulation of extract containing shikonin using gelatin-acacia coacervation method: a formaldehyde-free approach

The application of microcapsule for pharmaceutical dosage form for various drugs has received considerable attention in recent years due to its multiple advantages. The most frequently used crosslinking agent formaldehyde in the gelatin–acacia microencapsulation process was altered by glycerol in this study. The effect of various parameters such as the concentration of surfactant, concentration of gelatin and continuous phase pH condition on the microcapsule particle size distribution was experimentally investigated. It was shown that the optimum concentration for surfactant/oil ratio is 1/10 and gelatin/oil ratio is 1/5 in the pH condition of approximately 4–6 for the coacervation process. Results obtained from microscopy observation revealed that one core microcapsule prepared by 6% glycerol was no different from formaldehyde. Hence, glycerol was demonstrated to be a good potential non-toxic crosslinking material for the applications of encapsulated extract containing shikonin.     

Theoretical Postulation of Mass Spectral Quantity and Distribution in Competitive Dynamic Dendrimer Mixtures

The theoretical postulations of mass spectral quantities and distributions of the three dynamic combinatorial libraries (DCLs) of mechanically interlocked dendrimers ([4]rotaxanes, molecular weight up to 8 800 kDa) have been investigated. The number of different dendrimers in the three library mixtures is 4, 10, and 20. The theoretical postulations involve their macroconstants in a combination with statistical distribution, binding constant, steric, and hydrophobic effects. We found out that the mass spectral intensities which relate to the dendrimer quantities in a competitive mixture are not random, but with a predictable trend in terms of their macroconstants. This postulation agrees significantly well with most of the experimentally determined mass spectral intensities in the dendrimer mixtures.

     

Spectrophotometric determination of cobalt with chlorindazon DS

Summary The optimum experimental conditions for the spectrophotometric determination of trace amounts of cobalt(II) in aqueous solutions using chlorindazon DS were assessed and the procedure was described. A 5.5-fold molar excess of the reagent is required for complete complex formation. Heating at 60° for 20 min or at 100° for 5 min is required for complete colour development. The system conforms to Beer's law; the optimum range for a 1-cm cell is 0.4–1.4 ppm of cobalt, determined with a relative standard deviation of 0.5%. The molar absorptivity at 638 nm is 3.25×10⁴l mole^–1 cm^–1. Cyanide seriously interferes with the determination. A reaction ratio of 1 to 3 for cobalt to the reagent has been deduced from spectrophotometric data. This method was utilized to determine cobalt in a steel sample.

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Zusammenfassung Die optimalen Bedingungen für die spektrophotometrische Bestimmung von Kobalt(II)-Spuren in wäßrigen Lösungen mit Chlorindazon DS wurden ermittelt und die Arbeitsweise angegeben. Ein 5,5-facher molarer Überschuß ist für die vollständige Komplexbildung nötig. Zur endgültigen Farbentwicklung ist es nötig, 20 min auf 60° oder 5 min auf 100° zu erhitzen. Das Reaktionssystem entspricht dem Beerschen Gesetz. Die optimale Menge bei Verwendung von 1-cm-Küvetten ist 0,4–1,4 ppm Co, die relative Standardabweichung 0,5%. Die molare Extinktion bei 638 nm beträgt 3,25·10⁴l·mol^–1·cm^–1. Cyanid stört stark. Kobalt setzt sich mit dem Reagens im Verhältnis 13 um. Das Verfahren wurde zur Co-Bestimmung in Stahlproben verwendet.

     

Electrochemical techniques applied to the conservation of archaeological metals from Spain: a historical review

The conservation and restoration of archaeological metals is one of the most complex conservation issues. Therefore, conservators usually employ the most advanced techniques, with the purpose of obtaining positive results for the preservation of the objects. One of the aims of conservation treatments is avoiding the reactivation of corrosion processes. Electrochemical treatments applied on archaeological metals were employed in Spain since the beginning of the twentieth century. During its history, the treatments were praised and reviled, practiced and discontinued. Conservation criteria have also exerted an influence over electrochemical treatments. Nowadays, electrochemical techniques are provided with control devices, such as potentiostatic control and could be considered again as a very valuable option, in combination with traditional and vanguard techniques, to recover the archaeological metallic heritage.     

Development of HPLC with Photo‐diode Array Method for the Determination of Ramipril in Tablets Using Factorial Design

This study was to develop a liquid chromatographic method for the analysis of ramipril by the design of experiment. We first examined the effects of chromatographic parameters, such as column temperature, pH of mobile phase, flow rate of mobile phase and ion‐pairing reagents, on the isomerization of ramipril, and useda 2³ factorial design to optimize the chromatographic conditions. This optimized method demonstrated good system suitability and linearity within 1.0–50 µg mL^?1 (r2>0.999). The intra‐day and inter‐day precisions ranged from 0.4 to 2.7 %, and accuracy ranged from 98 to 100 %. The recoveries were greater than 99.2 %. The robustness test revealed the method remained unaffected by small deliberate variations of method parameters. This method was applied for the determination of ramipril in tablets. This study demonstrated that design of experiment was useful to efficiently assess the impacts of different parameters for analytical method development and optimization.