Automated Fraction Re-Analysis Does it really make sense?

Transcription

1 Automated Fraction Re-Analysis Does it really make sense? Presented by: Udo Huber 1995 PHD in organic chemistry from the University Karlsruhe/Germany Postdoctoral fellow at the University of Hawai i at Manoa Since 1997 Application Chemist with HP/Agilent Since 2000 Senior Application Chemist for the purification system and valve solutions Slide 1

2 Contents Introduction Why purification, why re-analysis? Where is my target compound? Workflow What is purity? Is my compound pure enough? Possible errors in automated fraction re-analysis The right point in the workflow to check the purity Other aspects A dedicated system for preparative and analytical work Sharing the DAD and MSD Slide 2

3 Why purification at all? O O R 1 X + R 2 R 3 R 1 R 3 Byproduct R 2 mau Starting material Target compound Impurities min Target compound goes to activity testing. Therefore it must be 100 % pure. Slide 3

4 Why re-analysis? 1. If more then one fraction was collected for the same sample re-analysis has to be done to identify the fractions containing the target compound. 2. Check purity of the target compound to make sure it is pure enough for activity testing. Slide 4

5 More then one fraction Why do I get more then one fraction? Time- or peak-based fraction collection To identify the right fractions I need: either standard for the compound analytical system or an MSD Prep system has no MSD if it had an MSD I didn t get more then one fraction analytical system Slide 5

6 Strategies for purification on a system equipped with MSD mau DAD 1-Vial 1 1-Vial 2 1-Vial 3 1-Vial 4 Peak-based fraction collection threshold only (50 mau) min MSD Vial 1 1-Vial 2 1-Vial 3 1-Vial 4 min Slide 6

7 Strategies for purification on a system equipped with MSD TIC Target mass: 241 amu Vial min EIC (242 [M+H] + ) Fraction containing target compound min Slide 7

8 Purity check Sample workflow 1.Sample submitted by chemist Solvent often DMSO/DMF 2.Sample purified Mobile phase water/acetonitrile 3.Fraction taken Mobile phase water/acetonitrile Slide 8

9 Sample workflow 4.Solvent evaporated Compound weighed 5.Compound re-dissolved Certain concentration, solvent often DMSO/DMF 6.Portion taken to activity testing (either DMSO solution, diluted with aqueous buffers or without DMSO) Rest of solution stored Slide 9

10 Important questions Confirm that target compound is going to activity testing, usually done by MS Measure purity of compound going to activity testing, must be higher then % Activity testing A representative portion of the sample going to activity testing must be reanalyzed to check the purity! Slide 10

11 What is purity? mau mau DAD: 254/8 nm (ref. 360/60 nm) 100 DAD: 204/8 nm (ref. 360/60 nm) MSD Compound did not ionize! min min mv ELSD Compound evaporated! 5 min min Slide 11

12 Break Number 1 Slide 12

13 Fraction re-analysis where in the workflow? Automated fraction re-analysis: Directly from fraction container (step 3) Advantage: High level of automation Disadvantages:??? Slide 13

14 Possible errors in when doing automated fraction re-analysis (1) fill mau time min Slide 14

15 Possible errors in when doing automated fraction re-analysis (1) mau 3500 Yellow Red No mixing when vial is filled! Blue Pink min Slide 15

16 Possible errors in when doing automated fraction re-analysis (1) T = 0 h T = 6 h T = 24 h T = 96 h Flow = 1 ml/min Flow = 4.5 ml/min Flow = 20 ml/min Slide 16

17 Possible errors in when doing automated fraction re-analysis (1) Portion drawn for reanalysis. Is this a representative sample? Slide 17

18 Possible errors in when doing automated fraction re-analysis (2) Portion drawn for reanalysis. Is this a representative sample? Sample was submitted in DMSO Mobile phase is water/acn Slide 18

19 Possible errors in when doing automated fraction re-analysis (3) Evaporation Sample decomposed while evaporated Dissolved in DMSO Portion taken to activity testing Portion drawn for reanalysis. Is this a representative sample? Do you do compound confirmation on a no-hit? Slide 19

20 What is the solution? What can I do??? Slide 20

21 Take a second sample from the solution that goes to activity testing! Let the purification system do what it was designed for! Use an analytical system to confirm compound and determine purity. Portion taken to activity testing Portion drawn for reanalysis. Is this a representative sample? Slide 21

22 Does this approach solve the problems? Fraction mixed before re-analysis Compounds dissolved before re-analysis Decomposition discovered during reanalysis Slide 22

23 Other aspects Using a combined inject/collector seriously compromises the pluming of the system and leads to additional broadening and therefore loss of recovery. At [ ] they see 90% recovery with our system and 60% with others You make a very good, in fact the best, analytical system already which is optimised for that specific job. All the labs interested have [Agilent] 1100 [Series] systems available to them for such use. A separate analytical system means our expensive Prep system is not tied up doing routine analysis as the real prep runs start to build up in a queue - Not cost effective. Performing re-analysis off line means you can specifically select which fractions you would like to re-analyse rather than all collected fractions being re-analysed. This eliminates unneeded analytical runs which are both time consuming and wasteful. Slide 23

24 Break Number 2 Slide 24

25 A single system for purification and analytical work Two separated systems absolutely no compromises regarding flow paths preparative AND analytical work in parallel Two systems sharing a single MSD and DAD can be operated with ChemStation only (rev. A.10.01), purification software and with Easy Access Plus not possible to do analytical and preparative work in parallel preparative autosampler and pumps used for analytical work (delay volume) Recommended for: Preparative flow rates up to 40 ml/min (1 inch columns) Injection volumes < 900 µl Analytical flow rates above ml/min (4.6 mm columns) Further details will be described in an Application Note Slide 25

26 The Agilent active splitter HPLC Flow Active Splitter MS Flow Slide 26

27 The Agilent active splitter Agilent active splitter provides control of the transfer of material from one flow stream to another. Rotor seal includes three selectable aliquot volumes (22 nl, 100 nl, or 300 nl). Gating frequency ( Hz) and aliquot volume determines the rate of mass transfer from source stream to destination stream. Slide 27

28 Two systems sharing a single MSD and DAD preparative work Waste Plug Splitter on Waste Slide 28

29 Two systems sharing a single MSD and DAD analytical work Waste Plug Splitter on Waste Slide 29

30 Two systems sharing a single MSD and DAD direct injection Waste Plug Splitter on Waste Slide 30

31 Automated fraction re-analysis does it really make sense? Introduction Why re-analysis, where is my target compound and what is purity? Possible errors in automated fraction re-analysis Concentration gradient Crystallization Decomposition How to avoid those problems? A dedicated system for preparative and analytical work Sharing the DAD and MSD Slide 31