Lab-on-a-chip miniaturized online liquid chromatography

Transcription

1 Lab-on-a-chip miniaturized online liquid chromatography Dr. Scott Gilbert Crystal Vision Microsystems, LLC Shoreline, Washington CPAC Satellite Workshop, Rome, Italy, March 20-22,2006

2 Lab-on-chip approach Compactness sensor-sized device Simplicity of operation Reduction of moving parts no (mechanical) pumps Robustness Inexpensive and facile maintenance 2

3 Conventional Process HPLC Dionex DX-800 Process Analyzer 3

4 Concept of a Modular LC Process Analyzer based on Lab-on-Chip NeSSI Generation III dream analyzer 4

5 Examples of commercially available microfluidic LC Nanostream s Brio 24-column parallel LC polymer cartridge Agilent s HPLC-Chip Veloce µ- parallel LC System LC/MS system 5

6 Design issues addressed Process stream sampling Gearing down, or reduction of macroflow to microflow Obtaining a representative sample 6

7 Split flow approach to sampling Liters per minute microliters per minute nanoliters per minute 7

8 Chip Layout Inlet lines 20mm Column Detector electrodes 8

9 Capillary geometries for open channel liquid chromatography d Conventional tubular capillary Ribbon or rectangular microchannel w d Advantage lower pressure drop with same diffusion path 9

10 Chip mount and lab set-up Air 10

11 Plug generation by flow-injection 11

12 Variable injection volumes Current [na] ms 1000 ms 500 ms 200 ms Time since injection [s] 12

13 Chromatographic behavior Current [na] 0.8 5mM Phenol 5mM Pentylphenol 2.5mM Phenol & Pentylphenol 0.6 OH Time since injection [s] 13

14 Resolution improvement by coated sol gel stationary phase Current [na] 3 No coating Sol-Gel coating Current [na] Time since injection [s]

15 Reproducibility of injections 10 ppm hydroquinone, phenol, trichlorophenol 90% methanol/h 2 O Amperometric response (na) Time (min) Amperometric response (na) Time (min) 15

16 Continuous reaction monitoring configuration Split flow 16

17 Schiff base formation aniline consumption 6 Amperometric response (na) Time (sec) Amperometric response (na) Time (min) 17

18 Monitoring of esterification reaction by chip-based liquid chromatography: Production of ethyl salicylate in ethanol under reflux - catalysed with nafion 117 Current (na) minutes 10.4 salicylic acid time (sec) Current (na) salicylic acid ethyl salicylate time (sec) 30 minutes chromatographic conditions: mobile phase: 10% MeOH-90%H 2 O / C8-coated channel. flow rate 50 nl/min detection amperometric +1.0V vs Pt. Run times under 4 minutes Rate data for reaction based on LC device measurements concentration (ppm) ethyl salicylate salicylic acid time (min) ethyl salicylate 18

19 On-line sample conditioning Concentrated stream diluent H-filter micromixer return waste Performs functions of : dilution filtration ph conditioning 19

20 Microreactor interfacing Parallel LC analysis platform 20

21 On-line Installation with CPC Microreactor at CPAC Laboratory, U. Washington 21

22 Advantages of this technology Integrated channels on monolithic substrate to replace conventional tubing Analyte sampling driven by line pressure Microchannels appropriate for open tubular LC Low pressure operation no need for a HPLC pump 22

23 Summary and Perspectives Continuous flow-through monitoring of chemical reactions Measurements under 4 minutes Operation pressures of under 1 bar Future work includes: Wall-coated polymer stationary phase for higher resolution separations Optimizing sample conditioning cartridges Building a modular analyzer prototype for testing larger volume reactors 23

24 Thanks for your attention! Lake Geneva Lake Washington Swiss Federal Institute of Technology, Lausanne (where we started ) University of Washington, Seattle campus 24

25 Q&A Hyperlinks Dionex process LC Split flow approach Variable injection Schiff base data Advantages Concept of module Split flow approach Chromatogra phic behavior Esterification reaction Summary & Perspectives Lab on Chip approach Chip layout Resolution improvement Sample conditioning Open tubular and capillaries Commercial chip LC Mount and setup Serial injections Microreactor interfacing Design equations Design Issues Injection images Continuous batch monitor CPC micoreactor Theoretical data 25

26 Design equations L = 4 d C P ηd φ m 1 2 N 1 2 C = ' '2 ( f0 + f1k + f2k ) ' ( 1 + k ) 2 t = d 2 L φη 2 Dm N 2 3 P, φ, η, D, N, k' fixed d can be tailored to optimize column efficiency (N) for chosen column transit time Mobile phase flow rates of only nl/min necessary driving pressures of < 1 bar (< 15psi) required to operate chip 26

27 Channel dimensions: 50µm x 10µm N=10,000 P P [bar] L [cm] Elution [s] Volumetric flowrate [nl/min] N=100,000 P P [bar] 0.5 L [cm] 32.9 Elution [s] 1000 Volumetric flowrate [nl/min]