Orthogonality considerations for library searching Nth-order data

✍ Scribed by Chad E Anderson; Reinaldo G Nieves; John H Kalivas

• Book ID: 104309575
• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 184 KB
• Volume: 41
• Category: Article
• ISSN: 0169-7439
• DOI: 10.1016/s0169-7439(98)00028-8

✦ Synopsis

Identification of chemicals from multi-order Nth-order instruments is typically carried out with only first-order library searches. Simultaneous library searches for all orders of Nth-order data enhances identification of chemicals. Three methods are presented for simultaneous Nth-order library searches based on measuring the angle between the unknown and reference Ž . chemicals present in a library. The first method, called first-order limited FOL , consists of unfolding Nth-order data to first-order and using the standard dot product function to compute the angle. The second approach, second-order limited Ž . SOL , unfolds Nth-order data to second-order and uses singular value decomposition to obtain the angle. The third method, Ž . Nth-order NO , computes the angle directly without unfolding. Performance evaluations show the advantages of SOL in search time for large libraries while FOL and NO appear to have a higher degree of selectivity. The methods of FOL and NO are shown to be the same measures but NO has a computational advantage. Computer memory usage for all three methods is also addressed.