Mass spectral interpretation using the "rule of '13'"

Molecular formulae of marine and terrigenous dissolved organic matter detected by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

“…In these cases Na ϩ duplicates were eliminated from the database. In a molecule containing only carbon and hydrogen the "rule of 13" can provide a base formula (Bright and Chen, 1983). By dividing the nominal mass of the unknown molecule by 13 (Eqn.…”

Two Flavones from <i>Acanthospermum hispidum</i> DC and Their Antibacterial Activity

“…Thus, the structure of compound 1 was established based on elemental analysis, UV-Vis., IR, 1 matic protons (δH 6.20 (s), 6.33(s), 6.56(s), 6.91(s)) which are typical of protons at C-6, C-8, C-3' and C-6' of a flavone skeleton [24] and two methoxy signals at δH 3.71(s)(3H) and 3.88(s)(3H). Based on the structural pieces of information from 1 HNMR, coupled with the use of the 'rule of 13' [25], the molecular formula was established to be C 17 H 14 O 8 .…”

“…IJOC in the B ring of the flavonoid ((MeO-4') and (AcO-5')). Based on the structural pieces of information from 1 HNMR and mass spectrum coupled with the 'rule of 13' [25], the molecular formula was established to be C 19 H 16 O 9 . The IR spectrum (KBr) indicated the presence of hydroxyl (3418 cm -1 ) and chromone (1646 cm -1 ) groups.…”

A new 16-membered tetraene macrolide JBIR-100 from a newly identified Streptomyces species

“…to the pluramycins, a group of structurally highly diverse reactive agents, possessing antimicrobial and anticancer activity [330] . The corresponding molecular formula of compound 220 was determined as C 24 H 20 O 6 , according to the Rule of 13 [331] . Accordingly, compound 220 exhibited close structural similarity to the hydroxyquinone mentioned above.…”