Computer techniques for identifying low resolution mass spectra

Grotch, Stanley L.

doi:10.1021/ac60305a015

Cited by 73 publications

(36 citation statements)

References 14 publications

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“…With special interest for the broad and unstructured UV/VIS spectra it is necessary to find out which criteria are best fitted to this kind of spectra. Mostly, the absolute deviation or Hamming distance [4,5], the Euclidian distance [6,11] and the correlation coefficient or even correlation functions [7,8] are used for an identification. Ebel and co-workers [9,10] compared the suitability of correlation functions and matrix rank analysis.…”

Section: Distance Criteriamentioning

confidence: 99%

A new fast and fault-tolerant identification algorithm for spectral databases

Wallwitz

Baumann

1996

Analytical and Bioanalytical Chemistry

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Section: Distance Criteriamentioning

confidence: 99%

A new fast and fault-tolerant identification algorithm for spectral databases

Wallwitz

Baumann

1996

Analytical and Bioanalytical Chemistry

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“…The performance of a retrieval system with regard to the relative behaviour of the comparison index, should be evaluated on the basis of the ranking of correct and incorrect matches for individual searches, executed with the spectra of the test set. As a measure of this behaviour, the recall as a function of the "confusion" [24] has been used. The confusion is defined here as the number of false positives with a Sr equal or better than the Sr of the target reference spectrum.…”

Section: Evaluation Of the C13rr Systemmentioning

confidence: 99%

An automated library search system for 13C-n.m.r. spectra based on the reproducibility of chemical shifts

Bally

Krimpen

Cleij

et al. 1984

Analytica Chimica Acta

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SUMMARYA library search system for 13C-n.m.r. spectra, based on a statistical description of the reproducibility of chemical shifts, is presented. A similarity index in the form of a significance probability (P-value) is developed from a previously introduced general concept. The applied data base of some 6000 spectra originates from the NIH-EPA Chemical Information System (CIS). The reproducibility model and the retrieval system are developed on a CDC Cyber 175 computer, with PASCAL as the programming language. The performance of the system is evaluated by using recall/reliability and confusion/ recall plots. In a tentative comparison with the Clerc search method (included in the CIS package), the Utrecht *fC-n.m.r. reproducibility-based retrieval system shows a better identification performance. The system is adaptable for use on a microcomputer.In recent years, several systems have been proposed for computer-aided library search of 13C-n.m.r. spectra, aiming at the identification of organic compounds and based on various coding and comparison algorithms [l-13]. Collections of several thousands of spectra, from different sources (i.e., recorded on different instruments, under various experimental conditions) are usually applied as data bases. Such data bases, which are often commercially available, generally suffer from poor interlaboratory reproducibility of the spectral data involved. In a previous paper [14], a new similarity index for "straightforward" library search methods was introduced, primarily for application to this type of data base. The main object of straightforward search methods is to retrieve the reference data (if available) of the unknown compound. This contrasts with "interpretative" methods, which aim principally at retrieving data of compounds similar in structure to the unknown. The proposed index has the form of a significance probability and is developed from a statistical model of the reproducibility of the quantities used for the comparison of unknown and reference data. Defined in general terms, this index is applicable to different types of analytical data, provided that the variables used to characterize unknown and reference spectra (feature quantities) are continuous in nature. In 13C!-n.m.r. spectra, the chemical shift and the peak intensity are such variables, in contrast to multiplicities. When a large multisource data base such as the CIS collection is used, how-

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“…The AND function was used initially (18) since this measures similarity and is the most obvious choice. The exclusive OR function (XOR) measures dissimilarity, and more importantly XOR is the binary analog of least squares, which lends a certain theoretical justification to its use (13,19).…”

Section: Evaluation Of Several Boolean Based Comparison Metricsmentioning

confidence: 99%

Quantitative evaluation of library searching performance

Delaney¹,

Warren²,

Hallowell³

1983

Anal. Chem.

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A procedure Is descrlbed for the quantltatlve evaluatlon of the performance of a llbrary searchlng system employed for molecular structure elucldatlon. The technlque allows the evaluatlon of any form of spectral representation or any spectral comparison metrlc. The approach Is applicable to any type of spectrometry used for llbrary searchlng (LS) or to comblnatlons of different types of spectra. All comparisons are made relative to a chosen standard of quallty for library searching performance. I t Is assumed that the results of searchlng a llbrary of full-Intensity, full-resolution spectra by a least-squares metrlc will provlde an acceptable standard for comparlson. Results are presented to demonstrate the utlllty of thls procedure for the examlnatlon of alternatlves for llbrary searching of vapor-phase Infrared spectra.Library searching (LS) has been used effectively for both the identification and interpretation of spectra. The continued interest in instruments such as the gas chormatography/ Fourier transform infrarled spectrometer (GC/FTIR) underscores the need for an objective approach to the development of versatile and efficient LS systems. The tremendous quantity of data which can be generated in a single GC/FTIR experiment necessitates computer-assisted data processing.Consequently, 1,s systems are included in most commercial GC/FTIR instruments.Two important choices must be made in the design of a library searching system: (1) the manner in which the spectra are to be processed prior to storage in the reference library, and (2) the comparison >metric to be used during the search. A diversity of options for each of these has appeared in the literature (1-9) but it is not clear what combination of options would provide the best L S system for a given application. As a result, the development of LS systems is typically approached empirically. Various possibilities are tried until "satisfactory" porformance is obtained. Commercial FTIR search systems reflect this problem, in that they generally offer a number of options for spectral processing and choice of search metric, with little guidance as to how to design an optimal searching system.The need for a quantitative evaluation of library searching systems has received some attention in the literature. LS systems designed for th,e identification of spectra are most easily treated. Here the goal is unambiguous. The search system succeeds if it gets the right answer. Quality for LS systems of this sort has been expressed as the percentage of correctly identified spectra (10).For interpretive LS systems, the problem is more complex. These systems are designed to give useful information for spectal interpretation even when the unknown spectrum is not present in the refer~ence library. The entire "hit-list" of closest matches thus becomes important in determining quality. The most cominon approach to assessing quality in such systems has been by subjective visual inspection of hit-lists (11). Such "evaluation by acclamation" is too qualitative to provide a soun...

show abstract

Computer techniques for identifying low resolution mass spectra

Cited by 73 publications

References 14 publications

A new fast and fault-tolerant identification algorithm for spectral databases

A new fast and fault-tolerant identification algorithm for spectral databases

An automated library search system for 13C-n.m.r. spectra based on the reproducibility of chemical shifts

Quantitative evaluation of library searching performance

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