EVOLUTION OF VACUUM PUMP REQUIREMENTS FOR LIQUID CHROMATOGRAPHY MASS SPECTROMETRY

Transcription

1 EVOLUTION OF VACUUM PUMP REQUIREMENTS FOR LIQUID CHROMATOGRAPHY MASS SPECTROMETRY Andrew Chew and Ian Olsen Edwards Global Technology Centre, UK This talk is based on that made at IVC-20 in Korea, August 2016 Wednesday 12 th October, 2016

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4 ABSTRACT 4 In addition to partial pressure analysis and leak detection, Mass Spectrometry incorporates a large vacuum market and application sector including Pharmaceutical, Medical and Life Sciences. In this paper we will focus on the historical evolution of primary and secondary vacuum pump requirements in Liquid Chromatography Mass Spectrometry (LCMS). This will be discussed in relation to pump types and capacity divergence, capital cost, cost of ownership, environmental impact, safety and communications protocols. Future trends and market developments will also be discussed

5 PRIMARY PUMPS 5 A primary vacuum pump is a pump that exhausts to atmospheric pressure Liquid Ring Diaphragm Typically operating in the continuum flow regime: Speed versus Displacement Oil Sealed Rotary Vane & Piston Scroll Screw Capacities ~1 to 2,000 m 3 /h Roots / Claw () Atmosphere

6 SECONDARY PUMPS 6 A secondary vacuum pump is a pump that continuously exhausts to a primary pump or requires a primary pump to create a level of vacuum it can operate from. It is often referred to as a high vacuum pump Other pumps include: Drag, NEG and TSP pumps Diffusion Ionization Cryogenic Turbomolecular Diffusion Ion Cryogenic Turbomolecular () Maximum Exhaust Pressure 10 3 atmosphere Typically operating in the molecular flow regime Capacities ~1 to 40,000 l/s

7 VACUUM PUMP CLASSIFICATION 7 Pump Type Entrapment Gases retained in pump Gas Transfer Gases moved and compressed Cryogenic & Ion Kinetic Positive Displacement Diffusion & Turbomolecular Scroll, Claw, Screw, Piston, Oil Sealed, Liquid Ring, Roots etc

8 WHAT IS A LIQUID CHROMATOGRAPHY MASS SPECTROMETER? 8 Analytical chemistry technique that combines physical separation capabilities of liquid chromatography (or HPLC) with the mass analysis capabilities of mass spectrometry (MS). Essentially, a mass spectrometer identifies chemical compounds Typical mass range from 100 to 50,000 amu cf RGAs 1 to 200 Used by forensic, environmental or clinical scientists, biochemists, homeland security specialists or food safety agencies e.g. medical application can span medical/clinical diagnosis, drug discovery, clinical trials and purity testing of the final product during their synthesis and manufacture

9 WHAT IS A LIQUID CHROMATOGRAPHY MASS SPECTROMETER? 9 Sample prepared and introduced Ionisation by different techniques eg ESI or APCI Analysers separate ions which have different mass-to-charge ratio. They are accelerated, focused or brought to resonance by electrical and/or magnetic fields Selected ions are directed into the detection chamber for quantification Results are output to a PC for data analysis Inlet + Source Analyser Ion Detection Sample Introduction Ionization Mass Sorting Detection Data Analysis

10 f x 0.1mm f x 0.1mm f x 1.0mm EXAMPLE LCMS - QUADRUPOLE 10 Air 200C 1000 sccm Higher Vacuum (Lower pressure) Chamber 1 1 to 3 Chamber x 10-3 Chamber x 10-6 What types of LCMS are there? Single quadrupole 1,500-3,000 amu Simple Ion trap 1,500-3,000 amu Triple quadrupole 1,500-3,000 amu Time of Flight 15,000-20,000 amu Quadrupole Time of Flight 16,000 30,000 amu FT Ion Cyclotron Resonance 40,000-50,0000 amu Sophisticated Split flow Turbo Backing Port High vacuum conditions prevent collisions of ions with residual molecules in the analyser during the flight from the ion source to the detector: they increase the efficiency of ion transfer and detection Primary/Backing Pump OR The function of a primary pump is to operate as a backing pump for the turbo-molecular pumps(s) and to remove carrier gas and/or solvent carry over

11 PRIMARY PUMP PROGRESSION 11 Sogevac SV40Bi Busch R5 Range Sogevac SV65Bi Agilent MS40+ 2 x Sogevac SV65Bi Sogevac SV120Bi 1990s nxl110i & nxl200i 25 slm Ebara EV-SA20 XDS35i XDS46i & XDS100B

12 LCMS VACUUM HISTORY: 1990S 2000S FUTURE 12 Primary pumps Typically operating in the 1 to 8 range Gradually increasing in size for improved sensitivity More recently smaller in size for entry level LCMS Wet to Dry - no oil to dispose of and typically lower power/heat

13 LCMS VACUUM HISTORY: 1990S 2000S FUTURE 13 Secondary pumps: TMPs Turbomolecular replaced (1990s) oil diffusion pumps - no accidents and lower CoO (power) Initially pure turbo stages and then additional drag stage (of various types) added. Splitflow pumps introduced in early 2000s reducing pump count Edwards adds third viscous regenerative stage

14 14 LCMS HISTORICAL PROGRESSION #1 CH1 CH2 CH3 780 sccm E E ls ls -1 Fully bladed turbomolecular pump exhaust pressure < m 3 h -1 8 m 3 h -1

15 LCMS HISTORICAL PROGRESSION #2 16 CH1 CH2 CH3 780 sccm E E-6 Drag stage turbomolecular pumps 240 ls ls m 3 h -1 Combined inlet and backing primary pump Twin discrete next240d

16 LCMS HISTORICAL PROGRESSION #3 17 CH1 CH2 CH3 780 sccm E E-6 One splitflow turbomolecular pump 200 & 200ls m 3 h -1 next Splitflow

17 LCMS HISTORICAL PROGRESSION #4A 18 CH1 CH2 CH3 780 sccm E E-6 Three stage splitflow turbomolecular pump 15 m 3 h & 200ls m 3 h -1 Smaller size primary pump next Splitflow + BOOST + aperture <

18 LCMS HISTORICAL PROGRESSION #4B 19 Increased inlet flow for improved sensitivity 1560 sccm CH1 2.0 CH2 4.0 E-3 CH3 1.0 E-6 Three stage splitflow turbomolecular pump 200 & 200ls m 3 h -1 Same size primary pump 30 m 3 h -1

19 LCMS HISTORICAL PROGRESSION FURTHER USE OF BOOST 22 Now triple quad mass spectrometer CH1 CH2 CH3 CH sccm E E E-7 Combined Boost from turbos 1 & 2 for high capacity viscous pumping 240 ls ls ls -1 Boost from turbo 3 reduces backing pressure for turbos 1 & 2 30 m 3 h -1

20 LCMS TMP CONFIGURATIONS 24

21 25 GENERAL CONSIDERATIONS - PRIMARY Oil in OSRV has to be disposed of - risk of accidents and or contamination, leaks (seal deterioration), spillages and suck-back Noise, both mechanical (vibration) and audible. Pumps are not necessarily the noisiest component in the lab OSRV often require the use of acoustic enclosures to reduce from 57 to 52dB(A): whereas scroll is 52dB(A) with better audible finger-print Power. Scroll pumps typically 50-60% lower power than equivalent OSRV (lower on reduced speed/stand-by mode). Usually inverter driven for consistent performance worldwide

22 26 GENERAL CONSIDERATIONS TURBOPUMPS Optimisation of turbopumps means significantly fewer pumps (power) needed Increased gas flows and/or better vacuum levels now possible Footprint newly introduced pumps should be backwardly compatible with previous versions but bring performance benefits Serviceability many users perform their own maintenance and service pumps Cost-of ownership Uptime no risk of oil accident (compared to diffusion pumps) Control and communications: parallel, serial or manual

23 SERVICE REQUIREMENTS 27 Drivers are: cost, up-time, end-user serviceability OSRV: Oil change (2 to 6 months) can take 24 hours to recover performance nxds scroll pumps: up to 5 year bearing service interval.(check performance after 2.5 years: tip seal may not need replacing if ok for Application) next TMP - oil reservoir lubrication service every 2 years end-user 10 mins

24 CLEANLINESS EVALUATION 28 P R DAVIS, R A ABREU AND A D CHEW, DRY VACUUM PUMPS A METHOD FOR THE EVALUATION OF THE DEGREE OF DRY (INVITED) JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY A, 18, (2000) Cap Man Gauge Fine Leak Valve (FLV) Hot Ionisation Gauge Quadropole Mass Spectromter Analysis Chamber Dry-Pump Under Test Pirani Gauge Exhaust Exhaust Turbomolecular Pump Rotary Vane Pump

25 29 INLET MASS SPECTRA - OSRV PUMP File : bhal1046 Date : E-6 18 (H 2 O) Pion = 1.6 x (N 2 /CO) Pline = <1.0 x 10-4 Time = >24 hours Partial Pressure () 1E-7 2 (H 2 ) E Molecular Weight (m/e) M/e =14 = CH 2 separation of groups

26 INLET MASS SPECTRA CONVENTIONAL AND XDS SCROLLS 30 1E-7 Pump D 14 (N) 32 (O 2 ) 69 (CF 3 ) Partial Pressure (Torr) 1E-8 1E-9 2 (H 2 ) 97 (C 2 F 3 O) 100 (C 2 F 4 ) 119 (C 2 F 5 ) Conventional scroll - PFPE peaks m/e = 69 and 119 from exposed bearings 1E-10 1E Pump A 14 (N) 32 (O 2 ) Molecular Weight (M/e) XDS - no bearings in vacuum space 2 (H 2 ) Partial Pressure (Torr) 1E-8 1E-9 69 (CF 3 ) 1E Molecular W eight (M/e)

27 KEY INGREDIENT FOR DESIGNING THE BEST SOLUTION 31 TransCalc HSM Used to predict vacuum system solutions with different flow rates, pressures, gas species and temperatures (like mass spectrometers). Used by Edwards engineers in collaboration Minimise number of hardware iterations and speed up instrument development time

28 SUMMARY Applications in the Instrumentation Sector have discrete and also common requirements for 32 Vacuum Wet to Dry primary and secondary Reduced # of pumps: single to split-flow TMPs and scroll pumps with multi function Environmental: power, cleanliness, no oil disposal. Pumps constant performance In-situ service Universal operation (inverters) Sophisticated Modelling predictive performance, reduced number of iterations

29 MERCI

30 EVOLUTION OF VACUUM PUMP REQUIREMENTS FOR LIQUID CHROMATOGRAPHY MASS SPECTROMETRY Andrew Chew and Ian Olsen Edwards Global Technology Centre, UK This talk is based on that made at IVC-20 in Korea, August 2016 Wednesday 12 th October, 2016