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Table 5 Assignment of the characteristic peaks

From: Chemical compositions, chromatographic fingerprints and antioxidant activities of Citri Exocarpium Rubrum (Juhong)

No. RT (min) UV (nm) MS in neg. mode MS in pos. mode MS2 in neg. mode MS2 in pos. mode Assignment References
1 15.2 283 / / / / Unknown /
2 18.3 282 / / / / Naringin /
3 19.2 253, 347 607 [M–H] 609 [M+H]+ 299 [M-Rutinosyl–H] 301 [M-Rutinosyl+H]+ Unknown /
     631 [M+Na]+     
     463 [M-Rhamnosyl+H]+     
     301 [M-Rutinosyl+H]+     
4 20.1 283 609 [M–H] 611 [M+H]+ 301 [M-Rutinosyl–H] 303 [M-Rutinosyl+H]+ Hesperidin [7, 19]
    1219 [2M–H] 1243 [2M+Na]+ 286 [M-Rutinosyl–CH3–H] 285 [M-Rutinosyl-H2O+H]+   
     465 [M-Rhamnosyl+H]+ 257 [M-Rutinosyl–CO2–H] 270 [M-Rutinosyl–H2O–CH3+H]+   
     303 [M-Rutinosyl+H]+ 242 [M-Rutinosyl-CO2-CH3-H] 195 [M-Rutinosyl–C6H4O2+H]+   
      134 [M-Rutinosyl-CO2–CH3–C6H4O2–H] 177 [M-Rutinosyl–C6H4O2–H2O+H]+   
5 23.3 283 609 [M–H] 611 [M+H]+ / / Neohesperidin /
     633 [M+Na]+     
     465 [M-Rhamnosyl+H]+     
     303 [M-Rutinosyl+H]+     
6 32.4 254, 347 723 [M–H] 725 [M+H]+ 417 [M-306–H] 419 [M-306+H]+ Unknown /
695 [M–CO–H] 747 [M+Na]+   
7 36.5 210, 257, 342 / / / / Unknown /
8 40.3 203, 269, 345 / 373 [M+H]+ / 343 [M–CH2O+H]+ Unknown /
     395 [M+Na]+     
     358 [M–CH3+H]+     
     343 [M–CH2O+H]+     
9 42.2 206, 253, 270, 355 / 403 [M+H]+ / 373 [M–CH2O+H]+ Unknown /
     425 [M+Na]+     
     388 [M–CH3+H]+     
     373 [M–CH2O+H]+     
10 43.6 214, 241, 330 / 373 [M+H]+ / 343 [M–CH2O+H]+ Sinensetin [20, 21]
     395 [M+Na]+   312 [M–H2O–CO–CH3+H]+   
     767 [2M+Na]+   297 [M–H2O–CO–CH2O+H]+   
     358 [M–CH3+H]+     
     343 [M–CH2O+H]+     
     312 [M–H2O–CO–CH3+H]+     
11 43.7 270, 295, 341 / 343 [M+H]+ / 313 [M–CH2O+H]+ Tetramethyl-O-isoscutellarein [20]
     707 [2M+Na]+   285 [M–CH2O–CO+H]+   
     328 [M–CH3+H]+     
     313 [M–CH2O+H]+     
     285 [M–CH2O–CO+H]+     
12 46.3 208, 336 / 403 [M+H]+ / 388 [M–CH3+H]+ Hexamethoxyflavone [21]
     373 [M–CH2O+H]+   373 [M–CH2O+H]+   
       355 [M–CH2O–H2O+H]+   
       327 [M–CH2O–H2O–CO+H]+   
13 47.1 333 / 403 [M+H]+ / 388 [M–CH3+H]+ Nobiletin [7, 20, 22]
     388 [M-CH3+H]+   373 [M–CH2O+H]+   
     373 [M-CH2O+H]+   343 [M–2CH2O+H]+   
       313 [M–3CH2O+H]+   
       283 [M–4CH2O+H]+   
       239 [M–C10H12O2+H]+   
       211 [M–C10H12O2–CO+H]+   
14 47.7 266, 322 / 343 [M+H]+ / 313 [M–CH2O+H]+ Tetramethyl-O-scutellarein [20]
     365 [M+Na]+   299 [M–CO2+H]+   
     328 [M-CH3+H]+     
     313 [M-CH2O+H]+     
15 50.1 253, 343 / 433 [M+H]+ / 403 [M–CH2O+H]+ 3,5,6,7,8,3′,4′-Heptamethoxyflavone [7, 20]
     455 [M+Na]+   373 [M–2CH2O+H]+   
     496 [M+Na+CH3CN]+   345 [M–2CH2O–CO+H]+   
     418 [M-CH3+H]+     
     403 [M-CH2O+H]+     
16 51.8 270, 323 / 373 [M+H]+ / 343 [M–CH2O+H]+ Tangeretin [7, 20, 22]
     395 [M+Na]+   283 [M–3CH2O+H]+   
     358 [M-CH3+H]+   312 [M–CH3–H2O–CO+H]+   
17 56.5 203, 254, 282, 341 / 389 [M+H]+ / 374 [M–CH3+H]+ 5-Hydroxy-6,7,8,3′,4′-pentamethoxyflavone [7]
     411 [M+Na]+   359 [M–CH2O+H]+   
     374 [M-CH3+H]+     
     359 [M-CH2O+H]+