Method Development for Chiral LC/MS/MS Analysis of Acidic Stereoisomeric Pharmaceutical Compounds with Polysaccharide-based Stationary Phases Liming Peng, Swapna Jayapalan, and Tivadar Farkas Phenomenex, Inc, 411 Madrid Ave, Torrance, CA 951 USA P8782611_L_1
Introduction Developing simple and straightforward reversed phase (RP) chiral LC separations coupled with highly sensitive MS detection is required for conducting drug metabolism and pharmacokinetic studies of stereoisomers and a challenging part of the drug discovery process We have presented our successful results on using polysaccharide-based stationary phases coupled with API-MS/MS detection for the analysis of various basic and neutral pharmaceutical compounds in reversed phase elution using NH4HC3 or NH4Ac as buffer salts and acetonitrile or methanol as organic modifiers 1 This investigation is extended to the effectiveness of using an acidic mobile phase for the separation and detection of acidic stereoisomers by ESI or APCI LC/MS/MS and to method development of Chiral LC/MS/MS analysis using polysaccharide-based chiral stationary phase (CSPs)
Figure 1 Structures of Chiral Phases Lux Cellulose-2 or-4 Cellulose tris (3-chloro-4-methylphenylcarbamate) or (4-chloro-3-methylphenylcarbamate) Cl Lux Amylose-2 Amylose tris (5-chloro-2-methylphenylcarbamate) Cl CNH CNH Cl Cl HNC CNH Cl HNC CNH Cl Lux Cellulose-1 Cellulose tris (3,5-dimethylphenylcarbamate) Lux Cellulose-3 Cellulose tris (4-methylbenzoate) CNH C Me HNC CNH Me C C Me
Figure 2 Molecular Structures of Acidic Racemates H S H Cl H F N H N H H H Ibuprofen Flurbiprofen Suprofen Fenoprofen Carprofen Indoprofen H NH N H H H N S N H B H C Proglumide H N Etodolac H Abscisic Acid H H N N H S Cl H Mecoprop Ketorolac 1-(Phenylsulfonyl)-3- indoleboronic acid Cl H N Cl CF 3 Cl N H S S S NH 2 NH 2 Warfarin Bendroflumethiaze Trichlormethiazide
Table 1 MRM Transitions and Concentrations of Acidic Racemates Compound IS and MRM Conc* Compounds IS and MRM Conc* Ibuprofen ESI - 251/161 1 Abscisic acid APCI - 263/1527 5 Flurbiprofen ESI - 243/1987 5 Mecoprop ESI - 2141/1417 5 Suprofen ESI + 2611/111 5 Ketorolac ESI - 254/298 5 ESI + 2562/15 Fenoprofen APCI - 241/1968 1 Etodolac ESI - 2861/242 5 Carprofen APCI - 2728/2288 1 Warfarin ESI - 371/169 5 ESI + 392/1631 Indoprofen ESI + 2821/2361 5 Bendroflumethiaze ESI - 421/779 5 Proglumide ESI - 3331/129 5 Trichlormethiazide ESI - 3778/2416 5 1-(Phenylsulfonyl)- 3-indoleboronic acid ESI - 3/298 1 * Conc (ng/ml)
Experimental Conditions Instrumentation HPLC System: Agilent 12 series Pump: G1312B (Binary Pump) Autosampler: G1337C HP-ALS-SL MS Detector: AB SCIEX API 4 LC/MS/MS -Turbo V Source with ESI or APCI probe MS Detection TurbolonSpray ESI or APCI in Positive or Negative Ion Mode; MRM transition HPLC Conditions Flow Rate: 2 ml/min (3 µm, 15 x 2 mm) or 1 ml/min (5 µm, 25 x 46 mm), flow split to 25 ml/min into MS/MS Injection Volume: 5 µl (15 x 2 mm) or 2 µl (25 x 46 mm) Columns: Lux Cellulose-1 3 µm 15 x 2 mm Lux Cellulose-2 3 µm 15 x 2 mm Lux Amylose-2 3 µm 15 x 2 mm Lux Cellulose-4 5 µm 25 x 46 mm Lux Cellulose-3 5 µm 25 x 46 mm Kinetex 26 µm C18 5 x 21 mm (used for achiral analysis) Mobile Phases: 1 Acetonitrile/Methanol: 1 % Formic acid (FA) 2 Acetonitrile/Methanol: 5 mm NH 4HC 3 achiral analysis 3 Acetonitrile/Methanol: 5 mm HCNH 4 (NH 4FA) achiral analysis 4 Acetonitrile/Methanol: 5 mm CNH 4(NH 4AC)- achiral analysis
Figure 3 LC/MS/MS Responses of Acidic Racemates in ESI - with Different Additives and Methanol 15 1 % FA:MeH 5 mm NH4FA:MeH 5 mm NH4HC3:MeH 5 mm NH4HC3:MeH 125 1 1 % FA:MeH 5 mm NH4FA:MeH 5 mm NH4HC3:MeH 5 mm NH4HC3:MeH 75 5 25 Warfarin Etodolac Ibuprofen Fenoprofen Flurbiprofen Proglumide Bendroflumethiaze 1-(PS)-3-indoleboronic Ketorolac Mecoprop Carprofen
Figure 4 LC/MS/MS Responses of Acidic Racemates in ESI- with Different Additives and Acetonitrile 5 mm NH 4 HC 3 : CN 5 mm NH 4 FA: CN 1 % FA: CN 5 mm NH 4 AC: CN 5 mm NH 4 HC 3 : CN 5 mm NH 4 FA: CN 1 % FA: CN 5 mm NH 4 AC: CN
Figure 5 The Effect of Acidic Additives on the Enantioseparation of Acidic Racemates in RP Bendroflumethiaze Lux 5 µm Cellulose-1 25 x 46 mm Flurbiprofen (pk a 433 ) Lux 5 µm Amylose-2 25 x 46 mm mau 4 DAD1D, Sig=22,8 Ref=off (F:\PHEN4157\HPCHEM\1\DATA\LP59\LP557D) 14642 15595 VWD1A, Wavelength=22nm(F:\PHEN4228\HPCHEM\1\DATA\LP31\LP3-22-121-2\LP3-22-121-3-222-12-32\LP-3- mau 35 947 3 161 3 2 1 A CN / 1 % HAc (4:6) Rs: 164 25 2 15 1 5 D CN / 1 % HAc (6:4) Rs: 272 mau 6 5 4 3 2 2 4 6 8 1 12 14 16 18 DAD1D, Sig=22,8 Ref=off (F:\PHEN4157\HPCHEM\1\DATA\LP59\LP554D) B Rs: 165 14915 15889 mi mau 6 5 4 3 2 2 4 6 8 1 12 14 VWD1A, Wavelength=22nm(LP31\LP3-22-1-221-3-231-52-16\LP-3-22-1-15D) 495 594 E CN / 1 % FA (6:4) Rs: 469 min 1 1 3256 mau 3 25 2 15 1 5 2 4 6 8 1 12 14 16 18 DAD1D, Sig=22,8 Ref=off (F:\PHEN4157\HPCHEM\1\DATA\LP59\LP5511D) C CN / 1 % TFA (4:6) Rs: 164 14954 15932 min 2 4 6 8 1 12 14 VWD1A, Wavelength=22nm(LP31\LP3-22-1-321-3-2311-47-19\LP-3-22-1-16D) mau 7 4628 6 5 4 3 2 1 F CN / 1 % TFA (6:4) Rs: 494 5581 min 2 4 6 8 1 12 14 16 18 min 2 4 6 8 1 12 14 min Conc: 25 µg/ml; Flow Rate: 1 ml/min; Injection: 1 µl; Detection: UV @ 22 nm HAc Acetic Acid TFA Trifluoroacetic Acid
Figure 6 The Effect of rganic Modifier on the Enantioseparation of Acidic Racemates in RP Proglumide Lux 3 µm Cellulose-1 15 x 2 mm Ibuprofen Lux 5 µm Cellulose-3 25 x 46 mm X I C o f -M R M (1 2 p a i rs ): 3 3 3 5 2 /1 2 9 D a fr o m S a m M a x 1 1 e 5 cp s X IC o f -M R M (1 2 p a ir s ) : 2 5 1 4 1 /1 6 9 D a fr o m S a m M a x 2 4 e 4 c p s 1 1 5 e 5 1 e 5 2 4 2 CN / 1 % FA (6:4) 2 e 4 CN / 1 % FA (6:4) 8 e 4 1 5 e 4 6 e 4 4 e 4 1 e 4 2 e 4 5 2 4 6 8 1 i X I C o f -M R M (1 2 p a i rs ): 3 3 3 5 2 /1 2 9 D a fr o m S a m M a x 3 6 e 4 cp s 2 4 6 8 1 1 2 1 4 X IC o f -M R M (1 2 p a ir s ) : 2 5 1 4 1 /1 6 9 D a fr o m S a M a x 6 3 5 9 c p s 3 6 e 4 3 e 4 6 5 CN / 1 % FA (5:5) 9 2 e 4 4 3 1 e 4 2 2 4 6 8 1 i X I C o f -M R M (1 2 p a i rs ): 3 3 3 5 2 /1 2 9 D a fr o m S a m M a x 1 6 e 4 cp s 1 2 4 6 8 1 1 2 1 4 1 a fr o m S a 1 7 1 X IC o f -M R M (1 2 p a ir s ) : 2 5 4 1 /1 6 9 D M a x 4 2 c p s 1 5 e 4 7 2 1 4 CN / 1 % FA (3:7) 2 8 4 1 e 4 3 5 2 1 2 4 6 8 1 FA Formic Acid 2 4 6 8 1 1 2 1 4 1 6 1 8 2 2 2 2 4 s
Figure 7 Enantioseparations on Lux Cellulose-2 with Acetonitrile or Methanol as Modifier X I C o f -M R M (6 p a i rs ): 3 3 3 5 2 /1 2 9 D a fro m S M a x 2 3 e 4 c p s X IC o f -M R M (1 2 p a ir s ): 3 3 3 5 2 /1 2 9 D a f ro m M a x 1 4 e 4 cp s 2 e 4 Proglumide 1 4 e 4 1 e 4 2 Proglumide Methanol / 1 % FA (7:3) n 2 4 6 8 t 1 1 2 e X I C o f -M R M (6 p a i rs ): 2 5 3 9 4 7 /2 9 8 D a fro m n M a x 5 7 8 5 9 c p s 2 4 6 8 1 1 2 1 4 X IC o f -M R M (1 2 p a ir s ): 2 5 3 9 4 7 /2 9 8 D a f ro m M a x 1 2 e 4 cp s 5 7 8 6 4 2 Ketorolac I 1 2 4 e 4 1 e 4 Ketorolac Methanol / 1 % Formic Acid (7:3) 2 4 6 8 1 1 2 X I C o f -M R M (6 p a i rs ): 4 2 4 8 /7 7 9 D a f ro m S a p M a x 1 3 e 4 c p s 2 4 6 8 1 1 2 1 4 X IC o f -M R M (1 2 p a ir s ): 4 2 4 8 /7 7 9 D a f ro m M a x 3 4 5 cp s 1 e 4 5 Bendroflumethiaze CH3CN / 1 % FA (4:6) 6 8 4 3 4 5 3 1 4 Bendroflumethiaze Methanol / 1 % FA (7:3) 2 4 6 8 1 1 2 p X I C o f -M R M (6 p a i rs ): 2 9 9 9 9 4 /2 9 8 D a fro m M a x 1 3 9 6 8 c p s 2 4 6 8 1 1 2 1 4 2 9 8 D a f ro m X IC o f -M R M (1 p a ir s ): 2 9 9 9 4 /2 9 M a x 2 2 1 cp s 1 3 9 7 1 5 1-(Phenylsulfonyl)-3-indoleboronic acid t 2 1 5 1-(Phenylsulfonyl)-3-indoleboronic acid Methanol / 1 % FA (7:3) 2 4 6 8 1 1 2 X I C o f -M R M (6 p a i rs ): 2 8 6 1 1 /2 4 2 D a fro m S p M a x 9 2 e 4 c p s 2 4 6 8 1 1 2 1 4 X IC o f -M R M (1 2 p a ir s ): 2 8 6 1 1 /2 4 2 D a f ro m M a x 1 7 e 5 cp s 9 2 e 4 5 e 4 Etodolac 1 5 e 5 1 e 5 Etodolac Methanol / 1 % FA (7:3) FA Formic Acid 2 4 6 8 1 1 2 2 4 6 8 1 1 2 1 4, c p
Figure 8 Enantioseparations in RP on Lux Cellulose-1 with Acetonitrile X I C o f -M R M (5 p a i rs ): 2 8 6 1 1 /2 4 2 D a fro m S a m M a x 3 e 5 c p s X IC o f -M R M (5 p a i rs ) : 3 3 3 5 2 /1 2 9 D a fr o m S a m M a x 2 8 e 4 cp s 3 e 5 2 e 5 Etodolac CN / 1 % FA (6:4) 2 8 e 4 2 e 4 Proglumide 1 e 5 1 e 4 2 4 6 8 1 T i m e, m in X I C o f -M R M (5 p a i rs ): 3 7 1 3 4 /1 6 9 D a fro m S a m s M a x 1 4 e 5 c p s 2 4 6 8 1 T im e, m in X IC o f -M R M (2 p a i rs ) : 2 7 2 7 6 1 /2 2 8 8 D a fr o m S a M a x 8 3 6 3 8 cp s 1 4 e 5 1 e 5 Warfarin CN / 1 % FA (6:4) 8 3 6 4 5 Carprofen APCI - CN / 1 % FA (6:4) 5 e 4 s 2 4 6 1 T i m e, m in X I C o f -M R M (2 p a i rs ): 3 7 7 7 7 4 /2 4 1 6 D a fro m S a m s M a x 1 5 e 5 c p s 2 4 6 8 1 T im e, m in X IC o f -M R M (5 p a i rs ) : 4 2 4 8 /7 7 9 D a fr o m S a m p M a x 1 1 e 4 cp s 1 5 e 5 1 e 5 Trichlormethiazide CN / 1 % FA (3:7) 1 e 4 Bendroflumethiaze 5 e 4 5 2 4 6 1 T i m e, m in X I C o f -M R M (1 2 p a i rs ): 2 9 9 9 9 4 /2 9 8 D a fr o m S s M a x 1 8 8 2 cp s 2 4 6 8 1 1 2 T im e, m in p a 4 D a fr o m S 4 3 X IC o f -M R M (1 2 i rs ) : 2 5 3 9 7 /2 9 8 M a x 9 9 5 cp s 1 5 1-(Phenylsulfonyl)-3-indoleboronic acid CN / 1 % FA (3:7) 4 3 2 Ketorolac CN / 1 % FA (3:7) 1 5 1 1 5 2 5 1 1 5 2 T i m e, m in T im e, m in FA Formic Acid c p s
Figure 9 Enantioseparations in RP on Lux Cellulose-4 with Acetonitrile X I C o f -M R M (6 p a i rs ): 2 8 6 1 1 /2 4 2 D a fro m S a m p l M a x 1 3 e 6 cp s X IC o f -M R M (6 p a ir s ) : 3 7 1 3 4 /1 6 9 D a fr o m S a m p l M a x 1 8 e 5 c p s 1 3 e 6 1 e 6 Etodolac CN / 1% FA (5:5) 1 1 5 e 5 1 e 5 Warfarin CN / 1 % FA (6:4) 5 e 5 5 e 4 t 2 4 6 8 1 fro m S a m X I C o f -M R M (6 p a i rs ): 2 9 9 9 9 4 /2 9 8 D a M a x 1 5 7 7 1 cp s 2 4 6 8 1 X IC o f -M R M (6 p a ir s ) : 2 5 3 9 4 7 /2 9 8 D a fr o m S a m M a x 4 5 5 6 1 c p s 1 5 1 1-(Phenylsulfonyl)-3-indoleboronic acid 4 Ketorolac 5 2 t 2 4 6 8 1 1 2 1 4 p a fro m S a m s 7 e X I C o f -M R M (6 i rs ): 3 3 3 5 2 /1 2 9 D a p l M a x 2 4 cp s 2 4 6 8 1 1 2 1 4 p 7 7 fr o m S a m 9 3 X IC o f -M R M (2 a ir s ) : 3 7 7 4 /2 4 1 6 D a p l M a x e 4 c p s 2 7 e 4 2 e 4 Proglumide 8 9 3 e 4 5 e 4 Trichlormethiazide CN / 1 % FA (3:7) 1 e 4 2 4 6 8 1 X I C o f -M R M ( 6 p a i rs ): 4 2 4 8 /7 7 9 D a fro m S a m p le M a x 1 2 e 4 cp s 2 4 6 8 1 1 2 1 4 p 4 D fr o m S a m 1 5 X IC o f -M R M (6 a ir s ) : 4 2 8 /7 7 9 a p l e M a x e 4 c p s 1 e 4 Bendroflumethiaze CN / 1 % FA (5:5) 1 5 e 4 1 e 4 7 Bendroflumethiaze CH3CN / 1 % FA (8:2) 5 5 2 4 6 8 1 2 4 6 8 1
Figure 1 Enantioseparations in RP on Lux Amylose-2 with Acetonitrile X I C o f -M R M ( 4 p a i rs ): 2 5 3 9 4 7 /2 9 8 D a fro m S a m p l M a x 2 4 e 4 cp s X IC o f + M R M (5 p a i rs ) : 2 5 6 1 8 9 /1 5 D a fr o m S a m p l M a x 2 2 e 5 c p s 2 e 4 1 5 e 4 Ketorolac 25395/298 (ESI - ) CN / 1 % FA (6:4) 4 1 9 2 e 5 1 5 e 5 Ketorolac 25619/15 (ESI + ) CN / 1 % FA (6:4) 4 1 9 1 e 4 1 e 5 5 5 e 4 1 2 3 4 5 6 7 8 X I C o f -M R M ( 4 p a i rs ): 3 7 1 3 4 /1 6 9 D a fro m S a m p l M a x 3 7 e 4 cp s 1 2 3 4 5 6 7 8 (5 p 9 1 1 a fr o m S a m M a x c p s X IC o f + M R M a i rs ) : 3 7 8 /1 6 3 D p l 7 e 4 3 7 e 4 3 e 4 2 e 4 Warfarin 3713/169 (ESI - ) CN / 1 % FA (6:4) 7 e 4 6 e 4 4 e 4 Warfarin 3918/1631 (ESI + ) CN / 1 % FA (6:4) 1 e 4 2 e 4 n 1 2 3 4 5 6 7 8 X I C o f + M R M ( 5 p a ir s ) : 2 6 1 1 2 /1 1 1 D a f ro m S a m p a x 1 3 e 5 cp s 1 2 3 4 5 6 7 8 X IC o f -M R M (4 p a ir s) : 2 4 2 9 5 4 /1 9 8 7 D a fr o m S a m p l M a x 3 5 e 4 c p s 1 2 7 e 5 1 e 5 Suprofen 26112/111 (ESI + ) CN / 1 % FA (6:4) 3 5 e 4 3 e 4 2 5 e 4 2 e 4 Flurbiprofen 24295/1987 (ESI - ) CN / 1 % FA (6:4) 5 e 4 1 5 e 4 1 e 4 1 2 3 4 5 6 7 8 5 1 2 3 4 5 6 7 8
Figure 11 Enantioseparations in RP on Lux Cellulose-3 with Acetonitrile Modifier X I C o f -M R M (9 p a i rs ): 2 1 4 1 2 /1 4 1 7 D a fro m S a m M a x 6 8 e 4 c p s X IC o f -M R M (9 p a i rs ) : 2 4 9 7 3 /1 9 6 8 D a fr o m S a m M a x 1 6 e 5 cp s 6 8 e 4 5 e 4 Mecoprop 2 4 6 8 1 1 2 1 4 1 6 T i m e, m in X I C o f + M R M (5 p a ir s ) : 2 6 1 1 2 /1 1 1 D a f ro m S a M a x 1 1 e 5 c p s 1 6 e 5 1 e 5 Flurbiprofen 5 1 1 5 2 2 5 T i m e, m in X IC o f -M R M (9 p a i rs ) : 2 5 3 9 4 7 /2 9 8 D a fr o m S a M a x 3 8 2 9 cp s 1 e 5 Suprofen (ESI + ) 3 8 3 Ketorolac 2 4 6 8 1 1 2 T i m e, m in i rs /2 4 a fro m S a c p X I C o f -M R M (9 p a ): 2 8 6 1 1 2 D m M a x 9 3 e 5 s 2 4 6 8 1 1 2 T im e, m in pairs 94/236 D a from S cps XIC of +M R M (2 ): 28 2 1 a M ax 5 9 e4 9 3 e 5 5 e 5 Etodolac 5 e 4 Indoprofen CN / 1 % FA (8:2) 2 4 6 8 1 1 2 T i m e, m in a /1 D a fr o m S c p X I C o f -M R M (1 2 p i rs ): 2 5 1 4 1 6 9 a M a x 3 9 e 4 s 5 1 1 5 T im e, m in D a fr o m S M X IC o f -M R M (1 2 p a i rs ) : 3 3 3 5 2 /1 2 9 a a x 3 1 e 4 cp s 3 9 e 4 Ibuprofen CN / 1 % FA (95:5) 3 1 e 4 Proglumide CN / 1 % FA (8:2) 2 4 6 8 1 1 2 T i m e, m in pairs 4973/929 from S am M cps XIC o f -M R M (2 ): 2 D a ax 6957 2 4 6 8 1 T im e, m in X IC o f -M R M (3 p a i rs ) : 2 6 2 9 6 8 /1 5 2 7 D a fr o m S a m M a x 2 4 e 4 cp s 6 9 6 5 Fenoprofen (APCI - ) 2 e 4 Abscisic acid (APCI - ) CN / 1 % FA (6:4) 5 1 1 5 2 2 5 2 4 6 8 1 1 2 1 4 T im e, m in T im e, m in, c p s
Results and Discussion Chiral LC/MS/MS experiments Five different polysaccharide-based chiral stationary phases Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, Lux Cellulose-4, and Lux Amylose-2 (Figure 1) were explored in the reversed phase elution mode for the separation of a variety of acidic compounds of pharmaceutical interest in mobile phases made of 1 % formic acid (FA) with acetonitrile or methanol as organic modifier and MS/MS detection Selection of mobile phase additives As acidic analyte presents as anion ion at the neutral ph, which is not suitable for retaining on polysaccharidebased CSPs and resulting in early elution without enantiseparation, the acidic additive is often used as a counter ion in mobile phase for suppression of dissociation of acidic analyte to increase the elution time and enantioselectivity of acidic racemates on CSPs Three acids - trifluoroacetic acid (TFA)- pk a 59; formic acid (FA) - pk a 375; acetic acid HAc) - pk a 476 were evaluated on Lux Cellulose-1 and Lux Amylose-2 CSPs as acidic additives In general, these additives provide similar enantioresolution for weakly acidic racemates (Figure 5, a, b, c) while the stronger acidic additive (TFA) performs better for the stronger acidic racemates (Figure 5, d, e, f) Formic acid provides comparable enantioseparations and peak shapes to TFA Considering the memory effect of TFA on polysaccharide-based CSPs and its ion suppressing tendency in MS detection, formic acid is preferred over TFA in RP MPs for the chiral separation and MS/MS detection of acidic racemates Effect of mobile phase additives The LC/MS/MS responses of acidic racemates with ESI in negative mode in 5 mm HCNH4, 5 mm CH3CNH4 and 5 mm NH4HC3 containing mobile phases with either acetonitrile or methanol as organic modifier using an achiral column Kinetex C18 were compared to responses in 1 % FA (Figure 3 and 4) The results show that MS/MS responses are comparable in 1 % FA CN or MeH to the responses of analytes in other additives considerd here in the ESI- mode This proves that 1 % FA as acidic additive in mobile phases is compatible for MS/MS detection and favored for enantioseparation of acidic racemates, except for carprofen which showed very poor responses in all of the additives at ESI - mode This proves that 1 % FA as acidic mobile phase additive is fully compatible with MS/MS detection of acidic racemates and can be implemented as the first choice Effect of organic modifier on chiral resolution Acetonitrile or methanol was used in chiral RP HPLC separations as organic modifiers Decreasing the eluting strength of the mobile phase by decreasing the portion of acetonitrile or methanol in the mobile phase will increase retention and resolution (Figure 6) However, once enantiomers elute later than 1 minutes with only partial resolution, baseline separation can rarely be achieved by further decreasing the % organic modifier in the mobile phase In our study, acetonitrile was more successful in providing chiral resolution on Lux CSP in RP mode compared to methanol (Figure 7) Chiral LC/MS/MS applications Figures 8-11 demonstrate 15 chiral separations on Lux CSPs APCI - source was employed for the MS/MS detection of carprofen, abscisic acid, and fenoprofen as APCI - provides much better MS/MS signals than ESI - for these three acidic racemates ESI + mode was used for the MS/MS detection of suprofen Most compounds evaluated here eluted in less than 1 min with baseline resolution in mobile phases of various eluting strength The results show that Lux Cellulose-3 was most successful in separating acidic racemates (1 racemates), especially non-steroidal anti-inflammatory racemates
Conclusions Fifteen successful chiral LC/MS/MS analyses are demonstrated for acidic racemic compounds on the polysaccharide-based CSPs Lux Cellulose-1, Lux Cellulose-2, Lux Cellulose-3, Lux Cellulose-4, and Lux Amylose-2 in reversed phase elution mode Formic acid as acidic additive in mobile phases is compatible for MS/MS detection and favored for enantioseparation of acidic racemates in RP Increasing the volume fraction of organic modifier (acetonitrile or methanol) in the RP mobile phase has the expected effect: it decreases retention and enantioselectivity; adjusting the organic modifier content of the mobile phase is essential to optimizing chiral resolution
References 1 Liming P, Tivadar F, Swapna J, Chirality 211 poster 2 HR Buser, MD Müller, Anal Chem 64 (1992) 3168 3 ML de la Puente, J Chromatogr A 155 (24) 55 4 SMR Stanley, WK Wee, BH Lim, HC Foo, J Chromatogr B 848 (27) 292 Trademarks Lux and Kinetex are registered trademarks of Phenomenex, Inc Agilent is a registered trademark of Agilent Technologies API 4 and Turbo V are trademarks of AB Sciex Pte Ltd TurboIonSpray is a registered trademark of AB Sciex Pte Ltd AB SCIEX is being used under license Disclaimer Phenomenex, Inc is not affiliated with Agilent Technologies or AB SCIEX Comparative separations may not be representative of all applications 211 Phenomenex, Inc All rights reserved