Data stations

Once a mass spectrum from an eluting component has been acquired, the next step is to try to identify the component either through the skill of the mass spectroscopist or by resorting to a library search. Most modem GC/MS systems with an attached data station include a large library of spectra from known compounds (e.g., the NIST library). There may be as many as 50,000 to 60,000 stored spectra covering most of the known simple volatile compounds likely to be met in analytical work. Using special search routines under the control of the computer, one can examine... 

PG workstations have become powerful, are simpler to use, and are generally ubiquitous within both laboratory and office environments. Using Wiadows-based software now widely available on instmment data stations as a basis for the LIMS will reduce the training costs and capital requirements when implementing a LIMS. 

Thermal Analysis - Differential Scanning Calorimetry (DSC) and thermal gravimetric analysis (TGA) were used to characterize the thermal properties of the polymers synthesized. DSC analysis was performed on a Perkin-Elmer Differential Scanning Calorimeter, Model 2C with a thermal analysis data station. Thermal gravimetric analysis (TGA) was carried out on a DuPont thermal gravimeter, Model 951. From the DSC and TGA plots of poly (N-pheny 1-3,4-dimethylene-... 

UV/visible 190-800 Cecil Instruments 5000 series (computerized and data station) Double High... 

Fluorescence spectra of the novolac samples were measured on a Spex Fluorolog 212 spectrofluorometer with a 450 W xenon arc lamp and a Spex DM1B data station. Spectra were taken with front-face Illumination using a 343 or 348 nm excitation wavelength for solutions or films, respectively, which are near the maximum transmission region of this spectrometer. Spectra were corrected using a rhodamlne B reference. Monomer fluorescence was measured at 374 or 378 nm and exclmer fluorescence was measured at 470 nm. Monomer and exclmer peak heights were used In calculations of Ie/Im. The 1 monomer peak of pyrene was used to reduce overlap with the exclmer emission. 

The glass transition (Ta) and melting (Tm) temperature of the pure component polymers and their blends were determined on a Perkin-Elmer (DSC-4) differential scanning calorimeter and Thermal Analysis Data Station (TADS). All materials were analyzed at a heating and cooling rate of 20°C min-1 under a purge of dry nitrogen. Dynamic mechanical properties were determined with a Polymer Laboratories, Inc. dynamic mechanical thermal analyzer interfaced to a Hewlett-Packard microcomputer. The... 

Instrumentation. UV/Visible spectra were collected on a Perkin-Elmer Lambda 4 spectrophotometer. IR spectra were collected on a Perkin-Elmer 1640 spectrophotometer. NMR spectra were taken on a Nicolet NT-200 spectrometer. Differential scanning calorimetry was run on a Perkin-Elmer DSC-4 unit, equipped with a system 4 microprocessor controller and a 3600 data station. Elemental analyses were run by the Purdue microanalysis laboratory in the Department of Chemistry at Purdue University and by Huffman Labs (Golden, CO). Lignin group analysis techniques are described in references 19-21. 

The GC analysis were effectued in a Perkin Elmer 8410 chromatograph with a 12 m capillary column of fused silica with associated BP-1 phase. IR spectra were recorded in the range of 4000-250 cm 1 using KBr disks, fluorolube or nujol mulls on a Perkin-Elmer 580B spectrophotometer, coupled to a M-3500 data station. 

GC equipped with a split injector, flame ionization detector or mass selective detector, and suitable chromatography data station... 

Collect the data and integrate the detector signal using a suitable chromatography data station. 

B) Bio-Rad Digilab FTS-60 Spectrometer with a Bio-Rad Digilab 3200 Data Station. 

A) 4206 Model Instron (with internal data station). 

Phosphorescence spectra (uncorrected, front face) were recorded on a Perkin-Elmer LS-5 fluorescence spectrometer using a pulsed excitation source ( 10 ps) and gated detection. The instrument was controlled by a P-E 3600 data station. The samples were typically excited at 313 nm using the instrument s monochromator and an additional interference filter. Excitation and emission bandpasses were 2 nm. Typically the emission spectra were recorded using a 50 ps delay following excitation and a 20 ps gate. The samples were contained in cells made of 3x7 mm2 Suprasil tubing, under a continuous stream of N2, 02 or 02/N2 mixtures of known composition. 

The IR spectrum of camphor as KBr disc and Nujol mull were recorded on.a Perkin Elmber 58O B Infrared spectrophotometer to which Infrared data station is attached (Fig. 3). The structural assignments have been correlated with the following frequencies (Table 3). 

The IR spectrum of reserpine as KBr-disc was recorded on a Perkin Elmer 58OB Infrared Spectrophotometer to which Infrared Data station is attached (Fig. l). 

A scaled saline or water reference spectrum was manually subtracted from each sample spectrum such that the region of the spectrum between 1700 cm and 2000 cm"1 was flat. Each subtracted sample spectrum was baseline corrected between 900 cm "1 and 2000 cm "1, and the peak height of characteristic protein and polysaccharide bands was determined using the baseline correct function and the cursor, respectively, on the Nicolet 660 data station. 

This chapter discusses features of the pump, injector, column, and detector. In addition, approaches to sample preparation are introduced. The data station is discussed in Chapter 7 under data handling. 

The detector converts a change in column effluent into an electrical signal that is recorded by the data station. Detectors in HPLC include... 

There are two purposes for using HPLC or CE determining the nature of the analytes in a sample and determining the concentration of each analyte. The former purpose is known as qualitative analysis, and the latter is termed quantitative analysis. The sample passes through the instrument and generates a signal that is recorded by the data station or strip-chart recorder. The signal must then be converted into qualitative or quantitative information. Data manipulation is the final step of the analysis. 

Most commercially available integrators and data stations have preprogrammed software routines for standard calculations. Before the area can... 

Spectrophotometry. Infrared spectra were obtained with a Perkin Elmer Model 281B Spectrophotometer interfaced with a computer data station. Films were encased in sample holders in the reference beam, and spectra were obtained with air as reference. The spectra were scanned from 1900 - 1500 cm-l at a scanning time of 60 minutes with a response setting of 2. The slit program was set at N. All spectra were recorded on computer disks. 

Another very broad field in chemistry not adequately covered on the software market is handling of spectral collection. There is, of course, a number of instrument producers that provide spectra handling software for their own instruments and data stations . Unfortunately, their software is mostly neither open for the users to modify it nor documented adequately to take full advantage of it. The worst example of such software does not even allow the user the access to raw data produced by the instrument and offers no possibility to transfer the data to other computers where processing according to users needs can be done. The potential buyers must be aware of such products, especially if they intend to work intensively on their own measured data, what is mainly the case in the R D laboratories. 

Today s predominance of the gas phase sequencer for sequence analysis is partly due to the advancement of PTH-amino acid analysis on HPLC, in which the analysis takes only 10 min to complete using reversed-phase column.70-72 Thus, a gas phase sequencer with an on-line PTH-analyzer can perform a single Edman degradation cycle within one hour. With the use of a microbore column and a data station which handles various data manipulations, a few pmol of PTH-amino acid can be quantitatively analyzed. Although the minimum detection level of amino acid derivatives has improved significantly in the last 10 years (103-104-fold enhancement), further improvement is expected with the use of a fluorescent compound, i.e., fluorescein isothiocyanate (FITC), and the laser detection technique. 

A few examples of the capabilities of automatic data stations are shown in Figure 7.9. The slope sensitivity can be set to distinguish between the... 

Figure 7.9. Examples of some methods of integrating areas of chromatograms with a computer data station.

Without doubt, however, the greatest difference between the two is that the sophisticated electronics of the newer instrument enable it to be directly connected to an Infrared Data Station , a microcomputer system which can smooth spectra, produce an average spectrum from a number of scans, subtract one spectrum from another, or reformat a spectrum. In addition, it is possible to identify possible structural features of an unknown compound and to match the spectrum against a reference library stored on magnetic disks, to facilitate a rapid identification of unknowns3). It is interesting to note that the basic optical specifications of the two instruments are not all that dissimilar ... 

Infrared spectra were recorded on a PE-580B instrument with data station. Lattice vibration spectra were obtained using the KBr technique. Hydroxyl spectra were scanned on self-supporting wafers of the samples mounted in a vacuum cell. Spectral averaging was usually 9 times. 

Data station- unit for instrument control and storage and processing of the experimental data... 

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