Use of mathematically enhanced spectral analysis and spectral contrast techniques for the liquid chromatographic and capillary electrophoretic detection and identification of pharmaceutical compounds

Swartz, Michael E.; Brown, Phyllis R.

doi:10.1002/(sici)1520-636x(1996)8:1<67::aid-chir12>3.0.co;2-q

Cited by 14 publications

(3 citation statements)

References 13 publications

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“…For example, selecting a low‐intensity ion for the denominator can result in large, but noise prone R isomer values . Another means of expressing isomer differences is through similarity indices or the spectra contrast angle (θ), defined as a dot product of spectral vectors A and B (Equation ) where A i and B i are the relative intensities of fragment

cos ϑ = \frac{\sum_{i} A_{i} B_{i}}{\sqrt{\underset{i}{false\sum} A_{i}^{2} \underset{i}{false\sum} B_{i}^{2}}}

…”

Section: Resultsmentioning

confidence: 99%

Stereospecific control of peptide gas‐phase ion chemistry with cis and trans cyclo ornithine residues

et al. 2017

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We report non-chiral amino acid residues cis- and trans-1,4-diaminocyclohexane-1-carboxylic acid (cyclo-ornithine, cO) that exhibit unprecedented stereospecific control of backbone dissociations of singly charged peptide cations and hydrogen-rich cation radicals produced by electron-transfer dissociation. Upon collision-induced dissociation (CID) in the slow heating regime, peptide cations containing trans-cO residues undergo facile backbone cleavages of amide bonds C-terminal to trans-cO. By contrast, peptides with cis-cO residues undergo dissociations at several amide bonds along the peptide ion backbone. Diastereoisomeric cO-containing peptides thus provide remarkably distinct tandem mass spectra. The stereospecific effect in CID of the trans-cO residue is explained by syn-facially directed proton transfer from the 4-ammonium group at cO to the C-terminal amide followed by neighboring group participation in the cleavage of the CO-NH bond, analogous to the aspartic acid and ornithine effects. Backbone dissociations of diastereoisomeric cO-containing peptide ions generate distinct [b ] -type fragment ions that were characterized by CID-MS spectra. Stereospecific control is also reported for electron-transfer dissociation of cis- and trans-cO containing doubly charged peptide ions. The stereospecific effect upon electron transfer is related to the different conformations of doubly charged peptide ions that affect the electron attachment sites and ensuing N-C bond dissociations.

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cos ϑ = \frac{\sum_{i} A_{i} B_{i}}{\sqrt{\underset{i}{false\sum} A_{i}^{2} \underset{i}{false\sum} B_{i}^{2}}}

…”

Section: Resultsmentioning

confidence: 99%

Stereospecific control of peptide gas‐phase ion chemistry with cis and trans cyclo ornithine residues

et al. 2017

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“…While several algorithms have been published for the utilization of hyphenated data for peak tracking [30,31] based on a spectral match angle approach [32], there are few commercially available tools. Multivariate "chemometric" approaches seem to have the most potential for future success.…”

Section: Lc/uv-vis and Lc/msmentioning

confidence: 99%

Computer‐Assisted HPLC and Knowledge Management

Kazakevich

McBrien²,

LoBrutto

2006

HPLC for Pharmaceutical Scientists

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“…Product-ion spectra, for example, can then be compared based on the derived spectral contrast angles (angles between vectors). Spectral contrast is used in many applications including voice recognition [2], astronomical satellite and aerial imaging [3,4], peak-purity determination in HPLC-UV [5], and in identification of oligonucleotides and peptides by HPLC-UV [6,7]. In mass spectrometry, spectral contrast is used in computer library searches of unknown EI spectra [8] and for peptide sequencing using tandem spectra and protein databases [9].…”

mentioning

confidence: 99%

Comparing similar spectra: From similarity index to spectral contrast angle

Wan

Vidavsky

Gross

2002

J. Am. Soc. Mass Spectrom.

215

164

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We investigated a spectral-contrast-angle () method to determine whether mass spectra of structural isomers are the same or significantly different. This method represents collisionally activated dissociation (CAD) spectra as vectors in space. Mass spectra of different isomers are represented as different vectors, having characteristic lengths and direction. The derived spectral contrast angle, which is a measure of the angle between two vectors corresponding to two closely related spectra, is a measure of whether the mass spectra are the same or significantly different. We compare this method with the similarity index (SI) method and show that the spectral contrast angle method is superior and can differentiate between very similar spectra in cases where the SI cannot. Both methods can be implemented simply in situations where the analyst is called on to decide, on the basis of mass or product-ion spectra, whether reference and unknown compounds are the same or to evaluate the reproducibility of spectra comprised of many peaks. (J Am Soc Mass Spectrom 2002, 13, 85-88)

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Use of mathematically enhanced spectral analysis and spectral contrast techniques for the liquid chromatographic and capillary electrophoretic detection and identification of pharmaceutical compounds

Cited by 14 publications

References 13 publications

Stereospecific control of peptide gas‐phase ion chemistry with cis and trans cyclo ornithine residues

Stereospecific control of peptide gas‐phase ion chemistry with cis and trans cyclo ornithine residues

Computer‐Assisted HPLC and Knowledge Management

Comparing similar spectra: From similarity index to spectral contrast angle

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