Utilizing NeSSI for Analytical ApplicationsDave Veltkamp*Brian Marquardt*Charlie Branham *Center for Process Analytical Chemistry (CPAC)University of Washington, Seattle WA Grad Student from Bart Kahrs group in Chemistry, UW

CPAC Project OverviewGoal is to support NeSSI related development within CPACDeveloping platforms and demo applicationsSupport PI and student use in research programs Promote and support wider NeSSI adoption and useWeb based supportInteraction with NeSSI communityLegal umbrella for cooperative development

Old NeSSI Gas/Vapor System

Optical Flow Cell Flow cell is a simple cross fitting6-around-1 fiber optic for source and collectionDelrin rod with sensing compound coated on endMultiple crosses can be chained together for screening several compounds at onceOptical detection using simple reflectance optical measurement Ocean Optics USB2000 VIS spectrometer (350-1000 nm)405 nm blue LED excitationCompound fluorescence signal in region 600-900 nm

Vapochromatic ResponseFull spectrum response of the 0%, 10%, and 50% bubbler flow samples used to make the PLS model showing both the change in intensity and shift in peak maximum with changing benzene concentration.

Vapochromic #1 Response* MFC #3 run at 5% FF rather than 50% FF

Vapochromic #3 Response

Bubbler Results (Benzene Conc.)Benzene concentration (ppm) calculated from the weight loss experiment data as a function of bubbler flow rate (%FF N2)

New Gas Sensor Testing SystemMore capability to generate analytical vapors, gas blending, and on-line dilution of vapor streams for method development workThis system delivered by CORCOR Tech to UM last week and will facilitate collaboration with Kent Mann

The New CIRCOR NeSSI System Has Arrived in Minnesota

Reconfiguration of CPAC NeSSI SystemOur Swagelok NeSSI system proven to be very easy to change to suit needsReplaced bubblers with permeation tubes and ovenChanged to look at CO2 in N2 blendingChanged to look at O2 and moisture in airInvestigation of flow, mixing, and dead volumesUsed to evaluated new analytical instruments in CPAC labASI microFast GC 2 column GC with trap injectionAspectrics EP-IR mid infrared spectrometer with gas cellLabVIEW software developed to automate experiments

Reconfigured NeSSI System

Schematic of SystemNeeded to design system with multiple (3) dilution stagesSomewhat complex flow paths to minimize dead volumesHad to compromise automated vs. manual control of N2 flows in first two stagesLack of additional MFCs required manual metering valves

System FlowsBy closing valves and using the MFCs as flow meters, all flows can be measuredClosing off the N2 flows (SV2 and MFC2) and waste valves (PV3 and PV4) allows flow thru bubbler to be measuredMFC3 and MFC1 set to valve open setpointAll flow streams and legs of system can be flushed by N2

System Flows (cont.)

Dilution Flows1st dilution of bubbler flow at input to MFC 3Most of flow goes to waste, MFC setpoint typically 1-5%N2 flow regulated by waste needle valve2nd dilution at outlet port of MFC 3Again most of flow going to waste, MFC 1 set to 1-5%N2 and 2nd diluted sample flows set by needle valves PV2 and PV43rd dilution at output port of MFC 1N2 flow controlled by MFC 2Important to balance pressures and flows to avoid unexpected flow conditions some tweaking required!!

Aspectrics EP-IR Instrument128 channels from 2.50 to 5.00 microns (4000-2000 cm-1)Each channel approx 19.7 nm wide band passAlso a 256 channel model availableRuns at an acquisition frequency of 100 scans (rotation) per secondReal-time data collection of fast eventsHigh averaging for low LOD applicationsSmall size and rugged constructionOnly moving part is the encoder diskSuitable for high vibration process environmentsNo hygroscopic partsSeveral optical configuration of sampling cell/accessories possiblePowerful on-line embedded chemometrics software

Aspectrics EP-IR Technology

Aspectrics EP-IR with Gas CellGlow sourceGas cellSpectrometer1575.2

ASI microFAST GCSystem on loan from ASI as part of WTC project with InfometrixProgrammed temperature gas chromatograph using Syringe or valve inlets to a flash evaporator. Sample delivery to an adsorbent trap for concentrationDesorbtion and delivery to twin capillary columnsTemperature programmed column elutionDetection by simultaneous flame ionization detectors (FID).Trace levels down to low parts per billion can be measured. Compact and easy to setup chromatographyWeight on the order of 12 poundsSize on the order of a shoe boxSpeed of analysis on the order of 10 times faster than competitorsVery easy to useTrap injection makes it simple to use and automateReally more like a spectrometer or sensor in operationEven non-chromatographers can use it!!

ASI microFAST GC

microFAST GC Column Details3 meter column length

microFAST GC Analytical CycleTypically 2-3 minutesTrap pre-purge timeEquilibrate timeTrap preheat timeInjection timeTrap cleanout timeColumn separation timeTrap cool-down timeColumn cool-down timeSample TimeAdjustable parameters that affect analysis lots of tuning potential

Interfacing to ASI microFast GC

Example Benzene ChromatogramsNot very demanding chromatography but convenient reference method

Experiment: Blending CO2 with N2Goal was to characterize the NeSSI system, software control, and the EP-IR gas cell data collectionSeries of step changes in MFC setpoints for CO2 dilutionDifferent hold times (delay) between setpoint changesSeries repeated 5 times Bubbler replaced with CO2 from tankResults show very good reproducibility and control of the gas blending systemDynamic response consistent with expectationsNo dead volume issues

CO2 Blending Experimental DesignNote: MFC #2 offset by 90%FF, numbers on plot represent step hold time

EP-IR Spectra from CO2 Experiment

1st PC of EP-IR Spectra PCA Model

Step times and Spectral ResponseNote: Total flow = 250 sccm, volume of cell ~ 210 ml so about 1-2 min exchange time (lag) seems about rightCO2 setpoints inverted & offset for clarity

CO2 Exp. Cycle Reproducibility

2nd PC of EP-IR Spectra PCA Model

PCA results showing nonlinear behavior at high CO2 conc.

On-line Chemometric Model Results

NeSSI Permeation TubesUsed a stainless steel condenser as oven for permeation tubesRemoved condenser core and replaced with permeation tubesMounted in single-port adapter to direct N2 up thru ovenSecond adapter block returns flow into NeSSI Temperature maintained by flowing water thru jacket from heater/chillerPermeation tubes made in-houseTeflon tubing sealed at both endsMade different tubes for water, benzene, and toluene vapors

Permeation Tube ResultsWater permeation tube studyVapochrome compound (Kafty) Oven temp. set at 50C MFC flow rate set at 10%, 20%, 30%, 40%, and 50% for 30 minSpectra taken at each flow rate Benzene permeation tube Vapochrome compound (#4) Oven temp. set at 30CMFC flow rate set at 0%, 10%, 20%, 30%, 40%, and 50% for 30 min Spectra taken at each flow rate

Conclusions and Future WorkSetup of NeSSI Vapor Platform complete (for now)LabVIEW software developed and testedFlow dynamics tested and characterizedNew vapor generation ideas to be testedNew instrumentation interfaced and testedBoth Aspectrics EP-IR and ASI microFAST GC valuable additional tools for monitoring gas mixing and deliveryAdditional applications from Sponsors welcomeVapochromic compound testing continuingMoisture, CO2, O2 and BTEX sensors testing underwayAdditional screening and analytical performance testing plannedPlan to get back to some microreactor work Parker NeSSI system for reactant and product streamsMicroreactor components from Microglass & IMM on handFuel cell studies with Eric Stuve and Chem. E. students plannedWTC Project with Infometrix on Process GC interfaced to NeSSI