Utilizing nessi for analytical applications
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Utilizing NeSSI™ for Analytical Applications. Dave Veltkamp* Brian Marquardt* Charlie Branham † *Center for Process Analytical Chemistry (CPAC) University of Washington, Seattle WA † Grad Student from Bart Kahr’s group in Chemistry, UW. CPAC Project Overview.

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Utilizing nessi for analytical applications

Utilizing NeSSI™ for Analytical Applications

Dave Veltkamp*

Brian Marquardt*

Charlie Branham†

*Center for Process Analytical Chemistry (CPAC)

University of Washington, Seattle WA

† Grad Student from Bart Kahr’s group in Chemistry, UW


Cpac project overview
CPAC Project Overview

  • Goal is to support NeSSI related development within CPAC

    • Developing platforms and demo applications

    • Support PI and student use in research programs

  • Promote and support wider NeSSI adoption and use

    • Web based support

    • Interaction with NeSSI community

    • Legal umbrella for cooperative development


Old nessi gas vapor system

1 MFC Controls N2 dilution flow

Single inlet line (N2)

Outlet lineto flow cell

Standard Ace Glass impingers

2 MFCs Control N2 flow to bubblers

Old NeSSI Gas/Vapor System


Optical flow cell
Optical Flow Cell

  • Flow cell is a simple cross fitting

    • 6-around-1 fiber optic for source and collection

    • Delrin rod with sensing compound coated on end

  • Multiple crosses can be chained together for screening several compounds at once

  • Optical detection using simple reflectance optical measurement

    • Ocean Optics USB2000 VIS spectrometer (350-1000 nm)

    • 405 nm blue LED excitation

    • Compound fluorescence signal in region 600-900 nm


Vapochromatic response
Vapochromatic Response

Full 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
Vapochromic #1 Response

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



Bubbler results benzene conc
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 system
New Gas Sensor Testing System

  • More capability to generate analytical vapors, gas blending, and on-line dilution of vapor streams for method development work

  • This system delivered by CORCOR Tech to UM last week and will facilitate collaboration with Kent Mann



Reconfiguration of cpac nessi system
Reconfiguration of CPAC NeSSI™ System

  • Our Swagelok NeSSI™ system proven to be very easy to change to suit needs

    • Replaced bubblers with permeation tubes and oven

    • Changed to look at CO2 in N2 blending

    • Changed to look at O2 and moisture in air

    • Investigation of flow, mixing, and dead volumes

  • Used to evaluated new analytical instruments in CPAC lab

    • ASI microFast GC – 2 column GC with trap injection

    • Aspectrics EP-IR mid infrared spectrometer with gas cell

  • LabVIEW software developed to automate experiments



Schematic of system
Schematic of System

  • Needed to design system with multiple (3) dilution stages

    • Somewhat complex flow paths to minimize dead volumes

  • Had to compromise automated vs. manual control of N2 flows in first two stages

    • Lack of additional MFCs required manual metering valves


System flows
System Flows

  • By closing valves and using the MFCs as flow meters, all flows can be measured

  • Closing off the N2 flows (SV2 and MFC2) and waste valves (PV3 and PV4) allows flow thru bubbler to be measured

    • MFC3 and MFC1 set to “valve open” setpoint

  • All flow streams and legs of system can be flushed by N2



Dilution flows
Dilution Flows

  • 1st dilution of bubbler flow at input to MFC 3

    • Most of flow goes to waste, MFC setpoint typically 1-5%

    • N2 flow regulated by waste needle valve

  • 2nd dilution at outlet port of MFC 3

    • Again most of flow going to waste, MFC 1 set to 1-5%

    • N2 and 2nd diluted sample flows set by needle valves PV2 and PV4

  • 3rd dilution at output port of MFC 1

    • N2 flow controlled by MFC 2

  • Important to balance pressures and flows to avoid unexpected flow conditions – some tweaking required!!


Aspectrics ep ir instrument
Aspectrics EP-IR Instrument

  • 128 channels from 2.50 to 5.00 microns (4000-2000 cm-1)

    • Each channel approx 19.7 nm wide “band pass”

    • Also a 256 channel model available

  • Runs at an acquisition frequency of 100 scans (rotation) per second

    • Real-time data collection of fast events

    • High averaging for low LOD applications

  • Small size and rugged construction

    • Only moving part is the encoder disk

    • Suitable for high vibration process environments

    • No hygroscopic parts

  • Several optical configuration of sampling cell/accessories possible

  • Powerful on-line embedded chemometrics software



Aspectrics ep ir with gas cell
Aspectrics EP-IR with Gas Cell

15”

7”

Spectrometer

5.2”

Gas cell

Glow source


Asi microfast gc
ASI microFAST GC

  • System on loan from ASI as part of WTC project with Infometrix

  • Programmed temperature gas chromatograph using

    • Syringe or valve inlets to a flash evaporator.

    • Sample delivery to an adsorbent trap for concentration

    • Desorbtion and delivery to twin capillary columns

    • Temperature programmed column elution

    • Detection by simultaneous flame ionization detectors (FID).

    • Trace levels down to low parts per billion can be measured.

  • Compact and easy to setup chromatography

    • Weight on the order of 12 pounds

    • Size on the order of a shoe box

    • Speed of analysis on the order of 10 times faster than competitors

  • Very easy to use

    • Trap injection makes it simple to use and automate

    • Really more like a spectrometer or sensor in operation

      • Even non-chromatographers can use it!!


Asi microfast gc1

dual columns and heater assembly

column

Fan

compartment

sheath

end of

finger

heated

head of

tight

columns

columns

connections

zone

Injector

Heater

FID Manifold

Back Panel

splitter

septa

flow

restrictor

Heated

FID Air

Sample Inlet

carrier

FID Vents

flow

removable

glass liner

V4(n open)

Injection

Trap &

FID

external

Heater

cooling

fuel

purge

fan

hydrogen

V2

V8

V1

V5

V3

@ 40psi

P

P

P

Ballast

electronic pressure regulators

Pneumatic Manifold

Injector

vent

Restrictor

Vacumn Pump

vent

vacuum

pump vent

ASI microFAST GC™


Micro fast gc column details

Columntemperaturesensor

column #1100 micron IDDB-5

Columnsoven sheath~1mm ID

column #2100 micron IDDB-1701

Columnheater

column heater sheath

microFAST GC™ Column Details

3 meter column length


Microfast gc analytical cycle
microFAST GC™ Analytical Cycle

Typically 2-3 minutes

Sample Time

Trap pre-purge time

Column cool-down time

Equilibrate time

Injection time

Trap cool-down time

Trap preheat time

Trap cleanout time

Column separation time

Adjustable parameters that affect analysis – lots of tuning potential


Interfacing to asi micro fast gc
Interfacing to ASI microFast GC™


Example benzene chromatograms
Example Benzene Chromatograms

Not very demanding chromatography – but convenient reference method


Experiment blending co 2 with n 2
Experiment: Blending CO2 with N2

  • Goal was to characterize the NeSSI™ system, software control, and the EP-IR gas cell data collection

    • Series of step changes in MFC setpoints for CO2 dilution

    • Different hold times (delay) between setpoint changes

    • Series repeated 5½ times

  • Bubbler replaced with CO2 from tank

  • Results show very good reproducibility and control of the gas blending system

    • Dynamic response consistent with expectations

    • No dead volume issues


Co 2 blending experimental design
CO2 Blending Experimental Design

Note: MFC #2 offset by 90%FF, numbers on plot represent step hold time



1 st pc of ep ir spectra pca model
1st PC of EP-IR Spectra PCA Model


Step times and spectral response
Step times and Spectral Response

CO2 setpoints inverted & offset for clarity

Note: Total flow = 250 sccm, volume of cell ~ 210 ml – so about 1-2 min exchange time (lag) seems about right


Co 2 exp cycle reproducibility
CO2 Exp. Cycle Reproducibility


2 nd pc of ep ir spectra pca model
2nd PC of EP-IR Spectra PCA Model




Nessi permeation tubes

dilution flow

NeSSI™ Permeation Tubes

  • Used a stainless steel condenser as “oven” for permeation tubes

    • Removed condenser core and replaced with permeation tubes

    • Mounted in single-port ½” adapter to direct N2 up thru oven

    • Second ¼” adapter block returns flow into NeSSI™

    • Temperature maintained by flowing water thru jacket from heater/chiller

  • Permeation tubes made in-house

    • Teflon tubing sealed at both ends

    • Made different tubes for water, benzene, and toluene vapors


Permeation tube results
Permeation Tube Results

  • Water permeation tube study

    • Vapochrome compound (Kafty)

    • Oven temp. set at 50°C

    • MFC flow rate set at 10%, 20%, 30%, 40%, and 50% for 30 min

    • Spectra taken at each flow rate

  • Benzene permeation tube

    • Vapochrome compound (#4)

    • Oven temp. set at 30°C

    • MFC flow rate set at 0%, 10%, 20%, 30%, 40%, and 50% for 30 min

    • Spectra taken at each flow rate


Conclusions and future work
Conclusions and Future Work

  • Setup of NeSSI™ Vapor Platform complete (for now)

    • LabVIEW software developed and tested

    • Flow dynamics tested and characterized

    • New vapor generation ideas to be tested

  • New instrumentation interfaced and tested

    • Both Aspectrics EP-IR and ASI microFAST GC™ valuable additional tools for monitoring gas mixing and delivery

    • Additional applications from Sponsors welcome

  • Vapochromic compound testing continuing

    • Moisture, CO2, O2 and BTEX sensors testing underway

    • Additional screening and analytical performance testing planned

  • Plan to get back to some microreactor work

    • Parker NeSSI™ system for reactant and product streams

    • Microreactor components from Microglass & IMM on hand

  • Fuel cell studies with Eric Stuve and Chem. E. students planned

  • WTC Project with Infometrix on Process GC interfaced to NeSSI™