Surface Measurement Systems Euro Food s Water, Brussels, Belgium: March 2006 pattwool@smsuk.co.uk
SMS - History Company formed in 1992/university spin-off Hotbed of innovation 10 Ph.D. s First Product Dynamic Vapour Sorption (DVS) 1993 DVS Microscope and Organic Vapour Options 1996 First commercial Inverse Gas Chromatograph 2000 Vapour Generator Instrument 2001 DVS High Throughput 2005
DVS Introduction Materials and Moisture How do materials interact with moisture in the environment? Effects stability, performance and safety of many materials. Isotherm - Equilibrium moisture content as a function of Relative Humidity. How much is taken up. Kinetics Moisture transport properties, how fast.
Limitations of Existing Techniques Saturated salt solutions: Very slow: weeks for one isotherm using static gravimetric saturated salt solution techniques. Labour intensive if many humidity levels required. Not able to study kinetics of sorption/desorption. Limited accuracy/precision.
DVS - Flowing Gas System Weigh sample continuously. Fully automated gravimetric instrument. Fast kinetics. Caking. Dynamic system - constant flow of gas ensures optimal mass transfer rate to and from sample - i.e. reaches equilibrium faster.
Dynamic Vapour Sorption Experiments may be completed in less than 24 hours. Entire system enclosed in temperature controlled environment - prevents condensation. Small sample size ( typically 1-100mg ) reduces time needed to establish equilibrium. Continuous monitoring of mass allows computer to decide when equilibrium is reached. Full control and monitoring of sample environment.
DVS Flow - Microbalance Digital recording ultra-microbalances: DVS Advantage - 1 Sample size up to 1.5 gm Mass change of +/- 150 mg with 0.1 µg resolution. DVS Advantage - 2 Ideal for larger food samples.
Kinetics of Moisture Sorption of Microcrystalline Cellulose 14 100 12 90 80 10 70 % Change in Mass 8 6 4 60 50 40 30 Relative Humidity (%) 20 2 10 0 0 500 1000 1500 2000 Time/mins 0 Moisture sorption behaviourofmicro crysta line ce lulose at25c-sorption onlyshown
Microcrystalline Cellulose - Isotherms 14.00 12.00 10.00 Change in Mass (%) 8.00 6.00 Desorption Sorption 4.00 2.00 0.00 0 10 20 30 40 50 60 70 80 90 100 Target RH (%)
Water Uptake Kinetics of Monosodium glutamate Kinetics of water sorption for monosodium glutamate dm - dry TargetRH 8 7 100 90 80 Change In Mass (%) - Dry 6 5 4 3 2 70 60 50 40 30 20 Target RH (%) 1 10 0 0 0 500 1000 1500 2000 2500 3000 3500 4000 Time in minutes
Spray Dried Milk Powder - Kinetics 14 100 12 10 Collapse of Amorphous Lactose Component 90 80 70 8 6 4 60 50 40 30 Relative Humidity (%) 2 20 10 0 0 500 1000 1500 2000 2500 3000 Time/mins 0
DVS- HT - The Next Generation
DVS-HT the High Thoughput Solution All new design. Fully automated operation. Multi-sample, high speed isotherm generation. 10 to 20 fold increase in efficiency over existing systems and technology. Designed for routine sorption analysis. No compromise data quality.
Carousel and sample pan
Avicel 10 HT samples Moisture Uptake for Avicel at 25C : 10 Sample Pans 90 110 80 70 108 % Change in Mass 106 104 Sam ple 1 Sam ple 2 Sam ple 3 Sam ple 4 Sam ple 5 60 50 40 30 Target % P/Po Sam ple 6 102 Sam ple 7 Sam ple 8 Sam ple 9 20 Sample1 0 10 % P/Po W ater 100 310 410 510 610 710 810 910 1010 1110 1210 Time / min 0
Avicel 10 HT samples + 1 DVS-1 sample Water Sorption Isotherms for Avicel at 25C: 10 DVS-HT Samples and 1 DVS-1 Samples 12.0 10.0 % Increase in Mass 8.0 6.0 4.0 2.0 DVS-1 HT Pan 1 HT Pan 2 HT Pan 3 HT Pan 4 HT Pan 5 HT Pan 6 HT Pan 7 HT Pan 8 HT Pan 9 HT Pan1 0 0.0 0 10 20 30 40 50 60 70 80 90 % Saturated Partial Pressure of Water
DVS-HT Dramatic lactose photos 29.1%RH versus 59.0%RH
Spray Dried Lactose/DVS-HT Dynamic Vapour Sorption High Throughput (DVS-HT) data Different amorphous contents. 12 100 100% Amorphous+duplicate 90 10 80 ChangeInMass(%)- Dry 8 6 4 2 0 0 0 100 200 300 400 500 600 700 800 DVS - TheSorptionSolution Target% RelativeHumidity Time/mins 75% Amorphous +duplicate 50% Amorphous 25% Amorphous 0% Amorphous SurfaceMeasurementSystemsLtdUK1996-2004 70 60 50 40 30 20 10 Relativehumidityin%
Sustained Release Capsules 90% RH t=0 hours 90% RH t=10 hours 1000µm
DVS - Applications Fast and Accurate Sorption Isotherms High Throughput option now available Caking, shelf-life and hygroscopicity measurements www.smsuk.co.uk Dr. Philip Attwool pattwool@smsuk.co.uk