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An HTML Approach to Creating and Maintaining a Chromatography Database atabases in analytical chemistry play an important role in identifying unknown compounds, especially in IR spectroscopy (1,2) and MS (3,4). The identification is accomplished by comparing the spectrum of the unknown against the spectra in the database. However, in research and development, when a pioneering study of chemical synthesis or reaction is being undertaken, the compounds of interest may not be identified by searching the database. Nevertheless the database is frequently useful for obtaining partial identification information from those compounds in the database that have spectral features similar to the unknown spectrum The creation and maintenance of a pyrolysis GC (pyGC) database of polymers have been described previously (5-7). However, these databases are in book form, as a collection of chromatograms in an electronic or hard-copy format, and the depth of information is limited. The search capability is restricted to a polymer index in the database or library. Users must literally carry the electronic files or books to have the database available. To create and maintain an electronic chromatography database certain issues must be addressed including inputting data from different sources maintenance (adding deleting and modifying entries) access and distribution compatibility and integration with
other databases, different computer platforms and the rnst
(see box on D 668 A) Hypertext markup language (HTML) Frank Cheng-Yu Wang The Dow Chemical Company S0003-2700(97)09031-8 CCC: $14.00 © 1997 American Chemical Society
HTML is used to create a datatase because it is simple to program, easy to understand, independent of computer platform, and efficient at linking files and images. (8) is a standardized language used on the World Wide Web (WWW). HTML is widely used and accepted because it is simple to program and easy to understand (because it is text based), is very efficient in linkingfilesand images, and is indepen-
dent of computer platform. This A/C Interface presents a small pyGC database that was created based on HTML. The software required to create, maintain, and view this database includes a text editor, an image editor, and a Web browser—the
Analytical Chemistry News & Features, November 1, 1997 6 6 7 A
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Software costs Software costs depend on the type of computer system used for the database. For purposes of illustration, a stand-alone IBM-PC system will be used as an example. The text editor comes with a Windows system. In Windows95, under the accessories category, the program Notepad ii a text editor program. One Web browser program, Microsoft's Internet Explorere comes with Windows95 as a combined package. There is no extra cost for the Exploree when Windows95 has been used as the Windows operation system. The image be processed in a Paint prowhich is a standard Windows95 accessory The WinGIFprogram ccn be used as a GIF format converter. WinGIF ii shareware that ti downloadable from the Internet; a $15 registration fee is required (http:// search.shareware.com/code/ engine/Findllogop=and&crrom= quick&orfile=True&htss=25& search=wingif&category=MSWindows%28all%29). The search software is called AltaVista Search Personal extension 97 which can be purchased from Digital Equipment Corporation for $29 95 Purchasing information can be found on the Web at httpV/www altavista software digital com/store/3ways/ index htm
most popular programs in today's Internet environment. Chromatography databases for GC, LC, TLC, supercritical fluid chromatography (SFC), and capillary electrophoresis (CE) have been available for many years (9-11)) The basic concept of chromatography is that an unknown mixture is carned by a mobile phase through a stationary phase to separate the mixture s components. 1 tie peaks in a chromatogram represent the number of components in that mixture and the relative elution and retention order of that specinc mixture under those experimental conditions. Eluuon order and reten668 A
tion time of peaks are affected by many factors, including the mobile phase, stationary phase, thickness of stationary phase, flow rate, and elution temperature. Because the retention time is highly dependent on experimental conditions, it may not be suitable as a search parameter in a database. To solve this problem, different types of retention indices have been developed (12-14). The most common is the Kovats retention index (12). Recently, the concept of retention indices has been further developed, especially in GC, to accommodate various experimental conditions (15,16). Even with retention indices there are still difficulties when chromatograms obtained from different types of stationary and mobile phases are compared This is one of the major reasons why there is no universal chromatography database widely available although there are small chromatography databases for
