Archiving spectra

Library search requires gas phase spectral databases (e.g. NIH/EPA) and archived spectra. For identification purposes temperature-programmed PyFTIR with appropriate data processing (differentiation, profile subtraction, etc.) has been used [835]. 

The MRS archival journal. Journal of Materials Research, already mentioned, is another broad-spectrum journal that has worked well, except for its limited polymer content. Here again, the principle of multiple editorship seems to have been an important component of success. 

Bottom panel Observed and synthetic Ha profiles for HD 140283 (black 5760K, grey 5560 K). The data was retrieved from the VLT archive (observing date 2000-06-15), reduced using REDUCE and rectified using parabolic fits to the continua in adjacent orders. Notice the variable telluric features which somewhat suppress the blue wing. An effective temperature of 5560 K (best estimate of [3]) is clearly too low, 5760 K (derived from the UVES POP spectrum) too high. At a S/N of 150, observational systematic errors are thus of the order of at least 100 K. 

Several historic wax samples were analysed successfully with GALDI-MS. It was found that a group of eighteen white seals from medieval documents (thirteenth to fourteenth century) from the archive of the Canton of Lucerne (Switzerland) all mainly consisted of beeswax. For example, the mass spectrum of a white seal from 1377 (inventory no. URK636/12663) is shown in Figure 5.14b. The typical pattern of beeswax, as described for the reference sample, can be clearly recognised. An additional peak at m/z 303 may be caused by abietic acid in the form of the molecule cation (C2oH3o02, MW 302), as found for rosin (see Section 5.3.2). This hints at the use of a diterpenoid resin, which was a common hardener for beeswax. A more detailed discussion of the composition of medieval white wax seals has been published elsewhere [57]. 

The flow of data through the system shown in Figure 1 depends on whether the experimental data are from a reference compound for the development of the library or from an unknown compound for analysis. Reference compound spectra are collected in the experimenter s data base and may be archived in the reference data base. They can also be matched against other spectra from other reference compounds by the spectrum matching program. When a match is found indicating that the two compounds have produced an... 

Figure 2 serves to illustrate the remarkable reproducibility and precision of the spectra that are obtained. The upper trace shows the 950-1150 cm-1 region of the absorbance spectrum of 35 x 10 3 Torr (buffered to 700 Torr total pressure with ultra pure air and run at forty meters path length) of supposedly 90% pure methanol, as received from a supplier. The middle trace represents 12 x 10 3 Torr of methanol, as determined more than a year previously in the short auxiliary cell. The lower trace shows the difference. Note that the and ISq spectra are completely distinctive, that the 1 0 enrichment is in fact only 65%, and that in the region of spectral overlap perfect separation of the two spectra can be achieved in spite of their great complexity. Further, the lower trace, obtained using archival reference data, represents a calibrated reference spectrum for methanol, even though no purified sample has ever existed. 

Calibration gas is then added to the zero (or scrubbed) air flow and allowed to stabilize for approximately 1 min. An averaged calibration spectrum is then obtained for 3 min which also serves as a reference spectrum and the raw data is archived (Figure 2b). 

Raps EC, Rogers JD, Galetta SL et al. (1993). The clinical spectrum of unruptured intracranial aneurysms. Archives of Neurology 50 265-268... 

Figure 1. Difference spectra of the officer s, new and archive vest yarns, referenced to spectrum of virgin yarn. (See page 3 of color insert.)...

Once the qualification results such as those in Table 10.5 are in hand, validation of instrumental accuracy should be conducted periodically. In the current example, a spectrum of the calcium ascorbate standard might be obtained each day, and stored in an archive. These spectra provide an immediate check on the position of the 767 and 1582 cm bands and may be accessed at a future date. If a particular sample spectrum comes into question, the calcium ascorbate spectrum for that day may be examined for any discrepancies. As noted earlier, a particular validation procedure will depend on the application, but a possible daily routine might include ... 

Cello JP, Fogel RP, and Boland CR (1980) Liquid caustic ingestion spectrum of injury. Archives of Internal Medicine 140 501-504. 

Palatnick W, Meatherall RC, and Tenenbein M (1991) Clinical spectrum of sulfonylurea overdose and experience with diazoxide therapy. Archives of Internal Medicine 151 1859-1862. 

J. G. Puig, A. D. Michan, M. L. Jimenez, et al. Clinical spectrum and uric acid metabolism. Archives of Internal Medicine 151, 726 (1991). 

With the ever-increasing need to improve quality and productivity in the analytical pharmaceutical laboratory, automation has become a key component. Automation for vibrational spectroscopy has been fairly limited. Although most software packages for vibrational spectrometers allow for the construction of macro routines for the grouping of repetitive software tasks, there is only a small number of automation routines in which sample introduction and subsequent spectral acquisition/data interpretation are available. For the routine analysis of alkali halide pellets, a number of commercially available sample wheels are used in which the wheel contains a selected number of pellets in specific locations. The wheel is then indexed to a sample disk, the IR spectrum obtained and archived, and then the wheel indexed to the next sample. This system requires that the pellets be manually pressed and placed into the wheel before automated spectral acquisition. A similar system is also available for automated liquid analysis in which samples in individual vials are pumped onto an ATR crystal and subsequently analyzed. Between samples, a cleaning solution is passed over the ATR crystal to reduce cross-contamination. Automated diffuse reflectance has also been introduced in which a tray of DR sample cups is indexed into the IR sample beam and subsequently scanned. In each of these cases, manual preparation of the sample is necessary (23). In the field of Raman spectroscopy, automation is being developed in conjunction with fiber-optic probes and accompanying... 

Durell SR, Lee C, Ross RT, Gross EL, Factor analysis of the near-ultraviolet absorption spectrum of plastocyanin using bilinear, trilinear, and quadrilinear models, Archives of Biochemistry and Biophysics, 1990, 278, 148-160. 

In conclusion, by insisting that the model results are routinely tested against the full spectrum of available palaeodata (from ice cores and other natural archives), we suggest that the study of past biogeochemical cycles can provide both a unique means to test complex earth system models and a powerful stimulus to their further development. 

A method able to classify compounds into various functional categories from their low-resolution mass spectra, similar to the method used by Crawford and Morrison, has been recently proposed by Smith >. A large set of reference spectra is reduced to a correlation set of ion-series spectra . Smith shows that each class of compounds that is available in an archive can be characterized by a typical ion-series spectrum. To determine the class of compounds to which an unknown substance should be assigned, the intensities of the signals found in its low-resolution mass spectrum are summed in the 14 different ion series calculated according to a formula similar to that used by Crawford and Morrison. Smith uses the following equation ... 

Micron-sized fillers, such as glass fibers, carbonfibers, carbon black, talc, and micronsized silica particles have been considered as conventional fillers. Polymer composites filled with conventional fillers have been widely investigated by both academic and industrial researchers. A wide spectrum of archival reports is available on how these fillers impact the properties. As expected, various fundamental issues of interest to nanocomposites research, such as the state of filler dispersion, filler-matrix interactions, and processing methods, have already been widely analyzed and documented in the context of conventional composites, especially those of carbon black and silica-filled rubber compounds [16], It is worth mentioning that carbon black (CB) could not be considered as a nanofiller. There appears to be a general tendency in contemporary literature to designate CB as a nanofiller - apparently derived from... 

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