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Design Team Nick Roulleau, Michael Vose Michael Racette, Michael McKay. Sterilization Device for Liquid Chromatography Solvents . Advisor Professor Mohammad Taslim. Introduction. Background Problem Statement Past Art Design Requirements Design Concepts Prototype Design
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Design Team Nick Roulleau, Michael Vose Michael Racette, Michael McKay Sterilization Device for Liquid Chromatography Solvents Advisor Professor Mohammad Taslim
Introduction • Background • Problem Statement • Past Art • Design Requirements • Design Concepts • Prototype Design • Component Analysis • Recommendations
What is Liquid Chromatography? A substance comprised of components A and B is dissolved in a solvent and enters the analytical column, where it is separated
Basic Components of an HPLC System From http://www.waters.com/WatersDivision
Problem From http://www.waters.com/WatersDivision
Design Goal To mitigate the risk of blockage at the inlet frit due to bacterial contamination and extend the useful life of the UPLC column.
Existing Solutions • In-line filters • Guard columns and cartridges • Pre-filtration of samples and mobile phase liquids
Product Requirements • Mandatory: • Must be adaptable for use worldwide • Must extend the useful life of columns • Must meet safety standards (ISO, UL and CE) • Must operate for 1 year w/o user intervention • Desirable: • Should be able to filter two bottles simultaneously • Should meet customer acceptance criteria • Low-maintenance • Easy to use • Cost
Constraints • Cannot change the chemical composition • Of the solvent • Of the sample • Cannot create risk of causing pump cavitation • Cannot hinder bottle accessibility • Cannot negatively impact system resolution
Initial Design Concepts UV Probe Pump/filter--Cap enclosure Pump/filter--External enclosure
Preliminary Design – UV Probe • Inexpensive • Simple Design
Why Not Use Ultraviolet Radiation as a Primary Solution? • Degradation of organic solvent modifiers (Low Risk) • Degradation of aqueous additives (Low Risk) • User safety from UV-C exposure (Medium Risk) • UV can inactivate but not remove bacteria
Filter Sizing • How many bacteria could be generated per year? • Logarithmic growth: • Assuming worst case • 100% replicating • Short generation time • Neglecting lag phases and cell death • Filter capacity = 107 CFU/cm2
Filter Sizing With logarithmic bacterial growth, filter area becomes exceptionally large in a short period
Current DesignExternal Filter Enclosure with UV Dual-head brushless DC pump UV lamp with multiple sterilization lines Pall AcroPak 200 filters
Filter Selection • Membrane with material compatibility • Sufficient capacity to contain 1 year of inactivated bacteria
Pump Selection Micro-diaphragm pump • Dual pump heads • Ability to run dry • DC brushless motor for long life
Pump Pressure Requirements • Pump must deliver sufficient differential pressure (Δp) to move fluid through filter • Darcy’s equation for porous media: L = membrane thickness p1 = pump-side pressure p2 = outlet pressure Q = flow rate k = permeability constant for filter A = effective filter area (EFA) µ = viscosity
UV Block Design A dA • 99.99% inactivation requires a UV dose of at least 40 mJ/cm2 for nearly all species of bacteria • Dose is a function of the irradiance (mW/cm2) and time of exposure (in seconds) Dose = Irradiance x time
UV Block Design 13 loops necessary with an 18W UV bulb and thin wall FEP tubing
Test Planning Pump Sensor Device Column • Verification Test • Does the Device Meet Design Requirement? • Pump Particle-Laden Water from Bottles With and Without Device • Compare Backpressure and/or Flow Rate
Test Results Backpressure was reduced by 28% when our device was used
Cost Analysis • Developed target costs by estimating: • Annual costs without the assistance of our device (excluding operational costs) • Savings in material costs by implementing our device • Potential savings for high-end users = $44,000 • Minimum estimated annual savings = $600 • Target production cost = $500 • Target prototyping cost = <$1500
Recommendations for Further Development • Improve manufacturability of the design • Simplify tubing system • Smaller pump • Custom filter size • Analyze effectiveness of UV with microbiological testing
Summary • Introduction to liquid chromatography • The problem and its source • Requirements of a good solution • Design considerations • Prototype design and analysis • Recommendations