Pigments samples

Analysts use reflected light microscopy to examine the surface of polymers. By changing the angle of illumination they can accentuate surface texture and other features of interest. Reflected light microscopy is well suited to the examination of opaque and pigmented samples. Polymer scientists make extensive use of reflected light microscopy when examining the fracture surfaces of failed samples. 

FIGURE 25.3 (a) The HPLC chromatogram of the extract obtained from a yellow-pigmented sample of... 

Gallery (London). The sample contained white lead and ultramarine blue pigments Sample collected from a painting on copper leaf by F. Boucher, dated 1 750, containing 1.8 1.0 0.3 31.0 [9]... 

G. Eulitz [13] studied the correlation between chemical constitution and tinctorial strength directly on dissolved pigment samples. He was able to exclude physical crystal parameters, such as particle size distribution and degree of dispersion, by achieving molecular dispersion. His analysis demonstrated the following ... 

Fig. 7 Particle size distributions of the same pigment sample as derived from images taken with a transmission electron microscope (left) and a scanning electron microscope (right).

Transmission spectra were taken immediately after allowing the pigmented samples to cool down to room temperature. Interpretation of the characteristic 570 nm band shows that at 180°C, all of the pigment crystals are dissolved, provided their concentration is small (0.005 and 0.01%, respectively). At 140°C, however, not all crystals are dissolved. Fig. 25 demonstrates that crystallization, taking place inside a sample rather than on its surface, is not completed even after years of storage [39],... 

A certain amount of shearing forces have to be applied in order to overcome the surface forces that maintain the adhesion between agglomerated pigment crystals. In practice, the shearing forces that are necessary to reduce the particles in a given pigment sample to smaller or even optimal particle size, i.e., the dispersibility of a pigment powder, depends on a number of factors ... 

Cut three pieces of 3-cm wide chromatography paper to a length of about 18 cm. Label the top of each paper with a number. Assign a number to each pigment sample used. Draw pencil lines about 5 cm from the bottom of the end of each paper. 

Bidigare, R.R., and C.C. Trees. 2000. HPLC phytoplankton pigments Sampling, laboratory methods, and quality assurance procedures. Pp. 154-161 in Ocean Optics Protocols for Satellite Ocean Color Sensor Validation, Revision 2, J. Mueller and G. Fargion, eds., NASA Technical Memorandum 2000-209966. 

Tafel analysis of these mixtures indicated that pigmenting samples consisted of pure azurite, pure smalt, and azurite plus smalt mixtures, concentrated in smalt molar percentages of 55%, 72%, and 85%. This can be seen in Fig. 4.11, where a frequency diagram illustrative of the use of selected azurite/smalt dosages is presented. 

Ketone False positive results may occur in highly pigmented samples, samples containing levodopa metabolites, or samples containing significant amounts of sulfhydryls. 

Thus there is a need for further experimental work to assess the relationship between the pigment composition of P. antarctica and dissolved iron concentrations as a function of irradiance. To this end, we are currently undertaking the analysis of pigment samples from iron-addition culture experiments conducted at irradiances > 20 nE m 2 s In addition, there are other factors that may limit the utility of pigment ratios such as Fuco Hex in assessing the physiological status and/or ambient growth conditions of... 

Reference spectra were obtained from standard organic pigments from the Forbes collection of the Conservation Center, Institute of Fine Arts, New York University, and from a few organic and inorganic pigments from various sources. Additional reference spectra were obtained from compounds reportedly used as medieval paint additives, such as dried egg yolk, egg white, calcium carbonate, and kaolin. The spectroscopic identification of compounds in pigment samples from the manuscripts that we report herein was based on a comparison of sample spectra with these reference spectra. 

Although the pigment was not successfully identified in this case, the information that egg tempera is present as the binding medium is a valuable characterization by itself. Egg yolk was also identified in spectra obtained from a different-colored pigment sample from the same manuscript. 

Figure 3. Spectrum obtained from a yellow pigment sample from MS 46 (300 scans). Abbreviations are as follows ...

Figure 4. Results of subtraction of egg yolk and calcium carbonate spectra from that of a yellow pigment sample...

Figure 10. Top Reference spectrum, of Prussian blue (100 scans). Bottom Spectrum of a blue pigment sample...

Over 150 pigment samples covering the spectrum of hues used in Cilician art were taken from the four manuscripts described above. The hues were differentiated both by visual assessment and by comparison with color chips from the Munsell Book of Colors (14). In addition, because both MS Freer 32.18 and MS W. 539 were painted by workshops, pigment samples were taken from all of the miniatures of recognizably different styles in these two manuscripts. 

Table I. Hue and Location of Pigment Samples from Folio 13 Verso, MS. W. 539 (A.D. 1262)...

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