Continuing Innovations in Reversed-Phase HPLC Column Technology

Transcription

1 Continuing Innovations in Reversed-Phase HPLC Column Technology Pittcon 2010 March 4, 2010 rlando, FL Ronald E, Majors Agilent Technologies Wilmington, DE USA

2 utline of Talk* RPC Innovations in Three Areas: Selectivity Stability Efficiency Future Directions Focus on commercial products, not research products Approach innovations from an historical perspective

3 Reversed Phase Trivia First reported RPC experiment (1950- A.J.P. Martin and Howard, Biochem. J. 46, 532 (1950)- LL partition paraffin oil and n-octane on diatomaceous earth First reported siloxane bonded phase used in RPC (1967-Aue and Hastings, Dalhousie University, Nova Scotia) First reported commercial RPC packing, Permaphase (polymer) on Zipax (1972-Kirkland, Dupont) First reported commercial RPC microparticulate packing, MicroPak-CH, 5-10-µm silica with monomeric C18 (1972-Majors, Varian) Reversed phase chromatography named by Csaba Horvath (dateunknown but around 1973) Approx % of all HPLC work performed by RPC [Horvath & Melander, J. Chrom. Sci. 15, 393 (1977)] 70-80% of all HPLC work performed by RPC (J. Chrom. Sci, Sept, 1980) LCGC 2009 survey showed 94% of all chromatographers use RPC

4 HPLC Analytical Column Pittcon Introductions by Phase ( )* (for RPC columns, 915 cumulative total) 2010 Number of Columns Specialty NPC RPC IEX SEC RPC Specialty IEX NP SEC * Extracted from my LC/GC Pittcon Articles

5 Rel ative % of Usage HPLC Mode Usage versus Year ( )* (Normalized to 100%) LCGC Surveys RPC NPC LSC Ion Exch SEC HILIC Chiral ther

6 Innovations in RPC Selectivity Base packing contribution Silica type (acidity), surface area, pore size, pore volume, etc. ther particles: alumina, zirconia, titania, polymer Chemical moiety contribution Bonding chemistry Monomeric- and polymeric-bonding (coating) Carbon loading, endcapping Mobile phase contribution Will not be covered here

7 The Surface of Silica Supports H H H H H Si Si Si Si Free Silanols Geminol Silanols Associated Silanols decreasing acidity M + M + Surface Metal H Si Internal Metal (activated silanol) (most acidic)

8 CH 2 -H. Chromatographic Improvement Using Highly Purified Type B Zorbax Rx-Sil riginal ZRBAX, 1973 and other type A silicas (basic compound can tail) CH 2 -H Conditions: Flow Rate: 2.0 ml / min. Mobile Phase: 5% 2-Propanol in Heptane ZRBAX Rx-Sil, 1987 and other Type B silicas (basic compounds have less tailing; lower effective silanol pka) 9

9 Zorbax StableBond with Rx-SIL Silica Type A More Acidic Column: DS, 4.6 x 250 mm, 5 m Plates: 92 USP T f (5%): 2.90 Improves Peak Shape Mobile Phase: 75% 50 mm KH 2 P 4, ph 4.4 : 25% ACN Flow Rate: 1.5 ml/min Silica Type B High Purity, Rx-Sil Column: SB-C18, 4.6 x 150 mm, 5 m Plates: 6371 USP T f (5%): 1.09 Propranolol pka 9.5 H CH CHCH NHCH(CH ) Time (min) Time (min)

10 Different C18 Bonded Phases for Maximum Selectivity 1 st choice Best Resolution & Peak Shape 2 nd choice Good alternate selectivity due to non-endcapped Eclipse Plus C18 StableBond SB-C18 Mobile phase: (69:31) ACN: water Flow 1.5 ml/min. Temp: 30 C Detector: Single Quad ESI positive mode scan Columns: RRHT 4.6 x 50 mm 1.8 um 3 rd choice Good efficiency & peak shape Resolution could be achieved 4 th choice Resolution not likely, ther choices better, for this separation ,3 4 4 Eclipse XDB-C18 Extend-C min Sample: 1. anandamide (AEA) 2. Palmitoylethanolamide (PEA) 3. 2-arachinoylglycerol (2-AG) 4. leoylethanolamide (EA) Multiple bonded phases for most effective method development. Match to one you are currently using.

11 RPC Bonded Phase Selectivity Differences in 30% ACN mau mau mau mau RRHT SB-CN 4.6 x 50 mm, 1.8 m RRHT SB-Phenyl 4.6 x 50 mm, 1.8 m RRHT SB-AQ 4.6 x 50 mm, 1.8 m RRHT Eclipse Plus C x 50 mm, 1.8 m 5 Different bonded phases compared Analysis time of each run is only 2 minutes Comparison done in optimum % organic The fast runs mean a comparison can be done even if you have a good separation on the C18 More chances to optimize! mau RRHT SB-C x 50 mm, 1.8 m 1 2

12 Reversed Phase Columns Introduced * # of Columns C18 C8 C4-C6 Polymer Phenyl CN C1-C3 Fluorinated Polar-embedded *My J. Chromatog. Sci, Anal. Chem. & LCGC Articles C30 ther

13 Shape Recognition in RPC Separation of EPA 16 Priority Pollutant PAHs NIST Standard Reference Material 1647 Through the adjustment of temperature the monomeric phase can yield a shape selective separation (decreased temperature) and the polymeric phase can loose shape selectivity (increased temperature). C.Rimmer, K.Lippa, & L. Sander, LCGC No. America, ct. 2008

14 mau Rapid Separation of PAHs on Polymeric RPC Column R s = x50mm, 1.8µm 1 = Toluene 2 = Naphthalene 3 = Acenaphthylene 4 = Acenaphthene 5 = Fluorene 6 = Phenanthrene 7 = Anthracene 8 = Fluoranthene 9 = Pyrene 10 = Benzo(a)anthracene 11 = Chrysene 12 = Benzo(b)fluoranthene 13 = Benzo(k)fluoeanthene 14 = Benzo(a)pyrene 15 = Dibenzo(a,h)anthracene 16 = Benzo(g,h,i)perylene 17 = indeno(1,2,3-c,d)pyrene Conditions: Agilent 1200SL DAD 220,4nm No Ref. DAD Stop Time = 5.60min Flow 2.00 ml/min Mobile Phase A = Water; B = Acetonitrile Gradient: Time (Min) % B Stop Time = 5.6 Temp. = 25 C 50 nanogm on Col for each Component no Mixer & no Pulse Dampener min

15 RPC Phases Beyond the Regulars Different alkyl chain lengths C12 (1997) C14 (1996) C20 (1994) C22 (1980) C27 (2005) C30 (1994) Mixed alkyl chains C18-Short alkyl (2002)

16 RPC Phases Beyond the Regulars (continued) Aryl phases Diphenyl (1991) Biphenyl (2008) Mixed alkyl-aryl C18-phenyl (1993) C6-phenyl (1998) Alkyl-polar Phenyl-CN (2008) C18-urea (2001) Phenyl-PE (1994) Biphenyl Restek Cartoons Diphenyl

17 RPC Phases Beyond the Regulars (continued) Polar-embedded Phases C18-carbamate (1998) C8-carbamate (1997) C18-polar embedded (2003) Alkylamide (1997) C8-amide (1999) C14-amide (1999) C23-amide (2000) C16-sulfonamide (2004) Phenyl-ether linkage (2001) Bonus-RP, ph polar alkyl phase 2. triple endcapped 3. uses bulky silanes CH3 Si CH3 CH3 Si CH3 R 1 Si R 1 CH3 R 1 Si R 1 CH3 R 1 Si PG PG PG R R R R 1 PG = amide R = isopropyl

18 RPC Phases Beyond the Regulars (continued) Alkyl-Ion Exchange C18-SAX (2001) C18-WAX (2007) C18-SCX (2002) C18-WCX (2007) C18-Basic group (2007) Phenyl-SCX (2006) C18-SCX-SAX (2009) (trimodal)

19 RPC Phases Beyond the Regulars (continued) Fluorinated Phases Pentafluorophenyl (PFP)/pentafluorobenzene (PFB) (1989) Fluorocarbon (1984) Fluorophenyl (1985) Perfluoroalkyl (2002)

20 ther RPC Phases Beyond the Regulars (continued) Hypercarb (Graphitized carbon) Graphitized carbon on Zr2 Pyridine (2008)-SFC PEG (2002) Cholesterol (2003) Hydrid (Type C silica) (2008) AQ-type phases

21 Polymeric RPC Columns Wide ph range (1-14) No silanols present Lower efficiency than silica-based columns (~1/3) Polymer-coated PBD on silica and alumina (1980) PBD on zirconia Representative chemistries PS-DVB (1977) C18-PS-DVB (1980) Polymethacrylates (1985) Polyvinylalcohol (1989) DVB (1990) PS-DVB-methacrylate (1996) DVB-methacrylate (1996)

22 Specialty RPC Columns HPLC columns developed for specific separations that are difficult to achieve on a standard column. Sometimes manufacturers will use a standard column but test it specifically for a certain class or compounds and provide a recommended set of chromatographic conditions. In some cases, the specialty column comes as part of a total solution kit with reagents, standards and a method. Most specialty columns will be delivered with a test chromatogram from an analysis performed at the factory before shipment and some are guaranteed for a specific separation

23 Examples of Specialty RPC Columns Fatty acid (1977) PAHs (1985) PTH-amino acid (1990) Triglyceride (1990) Peptide/protein (early 1970 s) Fullerenes (Bucky Balls) (mid-90 s) e.g. pyrene, pentabromobenzene Polar-embedded

24 Innovations in RPC Column Stability Packing base material Chemical bonding Packed bed

25 Base Material for All Columns (Not Just RPC) Introduced at Pittcon in Last 10 Years # of Columns Silica Polymer Hybrid Zirconia Monoliths

26 SILICA is THE Most Popular LC Packing Favorable Physical Characteristics: Spherical Shape Narrow Particle Size Distribution Uniform Porosity Narrow Pore Size Distribution Porous Throughout Choice of Particle Size 1.8, 2, 2.5 3, 5, 10, 15, 20 m Unfavorable Physical Characteristics: Soluble at high ph (ph > 9) Choice of Pore Sizes , 300, 1000Å Surface Easily Modified Choice of Bonded Phases Compatible with Water and All rganic Liquids Insoluble Unreactive Surface is weakly acidic (-Si-H), ionize at mid-ph Typical bonded phase ph range 2-8 (monomeric bonding)

27 Monomeric vs. Polymeric Bonding Monomeric Bonding Highly reproducible Polymeric Bonding figure courtesy of Grace Davison Trifunctional silane X = chloro- or alkoxy

28 Mechanism of Silica Bonded Phase Column Failure at Low ph Bonded phase cleavage Three Current Solutions: Hybrid phases Sterically-protected bonded phases Bidentate bonded phases

29 StableBond Reaction to Make a Sterically-Protected Surface (Kirkland, 1991) H 3 C H C CH 3 H 3 C H C CH 3 Si + Si Si Si H X R C C H 3 C H CH 3 H 3 C H X = Cl, Et, etc. R = CN, C8, etc. R CH 3 Diisopropyl silanes or diisobutyl silanes (C18)

30 ZRBAX StableBond Bonding (Kirkland, 1991) Low ph stability down to ph 1 Non-endcapped for selectivity and lifetime Patented sterically protecting bonding 6 different selectivities - C18, C8, CN, Phenyl, C3, Phenyl-hexyl For most sample types at low ph H H R Si R R Si R R Si R

31 Hybrid Silica-Carbon Particle (Xterra, Waters 1999) (courtesy of Waters)

32 Acquity 2004 XBridge BEH 2005

33 Mechanism of Silica Bonded Column Failure at High ph Silica Dissolution! Current Solutions: Protect the Silica High coverage, exhaustive endcapping Long bonded phase chains Bidentate bonding Polymeric phase Coated polymeric phase on inorganic support Hybrid Particle

34 ZRBAX Extend-C18 (Kirkland, 2000) Superior high ph stability up to ph 11.5 with silica particles Excellent reproducibility Patented bidentate, C18 bonding Double endcapping Si C18 Si C18 Si Si C18 C18

35 Lifetime of ZRBAX Extend-C18 at High ph (Kirkland, 2000) 180 Amount of Silica Dissolved, mg Eclipse XDB-C8 Eclipse XDB-C18 Extend-C18 Columns: Purge: Flow Rate: Temperature: 25 C Detection: 4.6 x 150 mm, 5 m 50% ACN / 50% 0.02 M K 2 HP 4, ph ml/min Silicate concentration by silicomolybdate color reaction Volume of Eluent, Liters

36 Chromatograms to Illustrate Phase Collapse in Reversed Phase Chromatography with Highly Aqueous Mobile Phase High Density C18 phase a) b) c) a) 40:60 H 2 :MeCN b) 100% H 2 (30 min) c) Recondition w/ 40:60 H 2 :MeCN d) & e) same experiment (all w/ 1% HAc) d) e) Polar-embedded C14 phase with ether linkage

37 (Before) Phase Collapse in Reversed Phase Chromatography Configuration of Long Chain Bonded Alkyl Phases in Water-Methanol Mixtures CH 3 H H 2 H 2 H 2 H 2 CH 3 H CH 3 H H 2 CH 3 H H 2 CH 3 H Si 2 H 2 H 2 CH 3 H CH 3 H H 2 CH 3 H H 2 H 2 CH 3 H Bonded moieties are fully extended from silica gel surface, are solvated and able to interact with analytes

38 Phase Collapse in Reversed Phase Chromatography Configuration of Long Chain Bonded Alkyl Phases in 100% Water (After) H 2 H 2 H 2 H 2 H 2 Si 2 H 2 H 2 H 2 H 2 H 2 H2 H 2 H 2 H 2 H 2 H 2 Bonded moieties are self-associated and in a collapsed structure

39 Possible Mechanism of Pore Dewetting ( Phase Collapse ) for Reversed-Phase Chromatography in a Highly Aqueous Mobile Phase Analytes Properly Retained Analytes Partially Retained or Unretained a) b) a) Pore Structure with pressure using a 100% aqueous mobile phase and alkyl chains in the pore properly solvated; analytes can partition into the pore and interact with nonpolar bonded phase b) b) Pore Structure after stopping the flow to allow expulsion of water from the pores; with flow resumed the pores are still dewetted and analytes cannot enter pores and have little or no retention Ref. J. E. Gara et al, LC/GC 19 (6) (2001).

40 Innovations in Efficiency of RPC Columns Particle size reduction Non-porous Porous Superficially porous* Monoliths * also called pellicular, porous layer beads, fused core, solid core

41 Future Directions in Particle Size Development (1973) Extrapolated line Majors & MacDonald, J. Chromatogr. 83, 169 (1973)

42 History of Commercial HPLC Particle Development Year(s) of Acceptance Particle Size Irregularly -Shaped Most Popular Nominal Size Plates / 15cm (Approximate) 1950 s 100µm 100 Glass Bead µm(pellicular) 1, µm 6, µm 12, µm 22, * 1.5 µm*(non-porous) 30, µm (pellicular) 8,000** µm 25, µm 32, / µm (pellicular) 32,000 *** * non-porous silica or resins ** 300 A pore for protein MW 5,700 *** A pore

43 Particle Size Usage in Analytical RPC Columns versus Year* % of Particle Sizes Particle Size, µm < * LCGC Magazine surveys

44 Average Particle Sizes for HPLC Columns Introduced at Pittcon 2010* 14 Number of Columns < >10 Aver. Particle Size, Microns Sub-two micron & superficially porous (2.7-µm) driven by high throughput applications & analysis of complex samples R. Majors, LCGC No. Amer. March, 2010

45 Recent Efficiency Improvements in HPLC Approach Specialized Instrument Required Key Advantages Major Limitations Sub-2 m Particle Yes/maybe Very high plate counts in short analysis times Extra-column broadening, frictional heating Superficially Porous Particle No High plate counts at relatively lower pressure Limited commercial phases High Temperature Yes (above 100 C) High efficiency maintained at high mobile phase velocity Solutes degradation, Limited number of stable stationary phases Silica Monolith No High column permeability Batch to batch reproducibility, Limited column dimensions & phases

46 Column Scalability: Change in Column Configuration to Increase Speed While Maintaining Resolution mau mau mau x 250-mm, 5 µm x 100-mm, 3.5 µm 4.6 x 50-mm, 1.8 µm 1 R 4,3 =9.30 R 3,2 =3.71 R 2,1 =4.31 R 4,3 =8.53 R 3,2 =3.37 R 2,1 = Column: Zorbax SB-C18 A= 0.2% FA, B=AcCN w 0.2%FA (98:2) F=1.5 ml/min Inj. Vol: 2-,4-, 6-ul, respectively; Detector: DAD, 254-nm; Flowcell: 3uL, 2 mm flow path 2 R 4,3 =9.30 R 3,2 =3.61 R 2,1 = min min4 5 min 3 min. min 1.5 min. Solutes: 1-methylxanthine; 2) 1,3-dimethyluric acid; 3) 3,7-dimethylxanthine; 4) 1,7-dimethylxanthine 3 4

47 Commercial 2- and Sub-2-µm Totally Porous HPLC Columns* Manufacturer Product Name Aver. d P, µm Micro-Tech Scientific Phenomenex Imakt Zorbax Rapid Agilent Resolution Technologies HT/HD VisionHTAlltech (Grace Davison) ProntoPEARL Bischoff TPP Ace-EPS Bluerchid Knauer LaChromUltra Hitachi Nucleodur Macherey-Nagel Cogent Diamond MicroSolv& Technology Silica-C Microsil Emerald, rachem Epitomize Technologies Luna PinnacleRestek DB/ Ultra II GP-8 andsepax GP-18 Pathfinder Shant Laboratories Capcell Pack Shiseido HypersilThermo Gold TSKgel SuperDS Tosoh Haas Acquity BEH Waters Ultra-FastYMC ZirchromZirchrom Fortis 1.7Fortis Technologies Epic Sub-2 ES Industries Presto Pursuit UPS Varian * Non-porous & Superficially Porous Particles Not Included Rapid asbagela Technologies 2.0

48 Commercial 2- to 3-µm Totally Porous HPLC Columns* Manufacturer Fortis Technologies Phenomenex Sepax Shimadzu Tosoh Bioscience Varian Waters Akzo Nobel Shant Laboratories Product Name Fortis Luna HST and Synergi GP-8 and GP-18 XR TSK-Gel DS HTP Pursuit UPS and XRS XBridge, SunFire Kromasil Eternity Pathfinder Aver. d P, µm 2.1, , * Non-porous & Superficially Porous Particles Not Included

49 Monolith Silica Support (Merck Chromolith, 2000) Monolith Rod Macroporous Structure (2-µm) Total Porosity 80% Mesoporous Structure (13-nm)

50 Van Deemter Plot A: HETP vs. Linear Velocity Small Porous Particle Columns and Silica Monolith (Chromolith) HETP (cm/plate) ZRBAX 5.0 m ZRBAX 3.5 m Vendor A 2.5 m Vendor B 2.0 m ZRBAX 1.8 m Monolith Dimensions: 4.6 x 50/30/20mm Eluent: 85:15 ACN:Water Flow Rates: ml/min Temp: 20 C Sample: 1.0 L ctanophenone in Eluent Equivalent to ~ 3.5-µm particle Interstitial Linear Velocity (u e )

51 Chromolith FastGradient (50-2mm) Fast Analysis of Steroids (Doping Substances) Mobile Phase: A-ACN B-H 2 Gradient: t A B flow [min] [%] [%] [ml/min] 0, ,50 0, ,50 2, ,00 2, ,00 2, ,00 3, ,00 Injection: 0,5µl Detection: 240 nm UV Temperature: 40 C Sample: 0 0,5 1 1,5 2 2,5 t [min] 1.) Fluoxymesterone 2.) Boldenone 3.) Methandrostenolone 4.) Testosterone 5.) Methyltestosterone 6.) Boldenone acetate 7.) Testosterone acetate 8.) Nandrolone propionate 9.) Testosterone propionate 10.) Nandrolone phenylpropionate 11.) Testosterone isocaproate (Courtesy of Merck KGaA)

52 Comparison of Diffusion Distances Totally porous silica versus superficially porous silicas 5 µm Totally Porous Particle 5 µm Superficially Porous Particle Poroshell 300 A 2.7 µm Superficially Porous Particle Poroshell 120 A 4.5 µm 1.7µm µm 0.25 µm 0.50 µm Required diffusion distance for a molecule

53 Poroshell 120 Columns for HPLC and UHPLC Poroshell 120 columns have: 80-90% efficiency of sub 2 µm At ~40-50% lower pressure 2X efficiency of 3.5 µm (totally porous) A 2.7 µm particle size A 2um frit to reduce clogging A 600 bar pressure limit The particle has a solid core (1.7 µm) and porous outer layer with a 0.5 µm diffusion path 53 Confidentiality Label March 8, 2010

54 P o r e V o l u m e ( c m ³ / g ) Poroshell 120 Pore and Particle Size Distribution BJH Adsorption dv/dlog(w) Pore Volume Particle Size Distribution Comparison with Totally Porous Particles Poroshell um totally porous 3.5um totally porous 5.0um totally porous ,000 Pore Width (Å) Poroshell 120 particles have an average pore size of 120 Å. Normalized Particle Size Distribution

55 Backpressure Comparison of 2.7µm Poroshell 120 with 1.8µm Totally Porous Particles Pressure (bar) Column Pressure (bar) vs Flowrate (ml/min) (60:40 ACN:H 2, all columns 4.6mm x 50mm) Poroshell 120 SB-C18, 2.7µm RRHT SB-C18 1.8µm System Pressure 1.8 µm totally porous particles 2.7 µm Poroshell Flow Rate (ml/min) Superficially porous particles have 40%-50% back pressure of 1.8 µm totally porous particles.

56 Van Deemter Curves Sub-2 µm, 3.5 µm, Superficially Porous 12 Van Deemters, 60/40 CH 3 CN/H 2, with RRLC measuring heptanophenone 10 8 h u (mm/s) Agilent Poroshell 120 EC-C18, 3.0 mm x 100 mm, 2.7 um (USCFX01009) Supelco Ascentis Express C18, 3.0 mm x 100 mm, 2.7 um (USKJ001754) Phenomenex Kinetex C18, 4.6 mm x 100 mm, 2.6 um ( ) Agilent ZRBAX Eclipse Plus C18, 3.0 mm x 100 mm, 1.8 um (USUYB01455) Agilent ZRBAX Eclipse Plus C18, 3.0 mm x 100 mm, 3.5 um (USUXV01435)

57 Fast Analysis (5cm) 2.7µm Poroshell 120 EC-C18 2.1x5 cm F = 1.94 ml/min, 40 C 56% ACN, 44% Water 549 bar mau t 0 = min t r = min N = 5,514 Log(t 0 /N)= min 1.8µm ZRBAX RRHD Eclipse Plus C18 2.1x5 cm F = 1.82 ml/min, 40 C 59% ACN, 41% Water 1003 bar mau t 0 = min t r = min N = 6,194 Log(t 0 /N)= min

58 Long Analysis (55cm) 2.7µm Poroshell 120 EC-C18 2.1x55cm (3x15cm, 10cm) F = ml/min, 40 C 56% ACN, 44% Water 547 bar mau t 0 = min t r = min N = 97,363 Log(t 0 /N)= min 1.8µm ZRBAX RRHD Eclipse Plus C18 2.1x55cm (3x15cm, 10cm) F = 0.23 ml/min, 40 C 59% ACN, 41% Water 1001 bar mau t 0 = min t r = min N = Log(t 0 /N)= min

59 Conclusions/Future RPC will continue to dominate HPLC separations Silica monoliths will continue to improve but will they be commercialized? Polymeric monoliths will become more practical for small molecule separations (less IP involved) Designer RPC materials for orthogonal separations (LCXLC) and for walkup RPC method development scounting systems Challenges: Packing small diameter columns efficiently with small particles Instrumental design keeping up with column developments (e.g. extra column effects, particle size, flow rate capability) LCGC Survey top reader dis-satisfiers: Column-to-column reproducibility (21%); lifetime (17%); price (14%)

60 Acknowledgments Manufacturers who supply me data for my Pittcon articles in LCGC Magazine Jason Link and other chemists at Agilent for providing slides from their presentations And you the audience for listening to my marathon presentation