A New Web-Based Application for Modeling Gas Chromatographic Separations Dr. Hansjoerg Majer Restek Corporation Market Development Manager Europe
The Method Development Process in GC $ SUCCESS!
Developing a new method Choose the best column: stationary phase Consult colleague Search for Literature Wish to see a chromatogram how well the stationary phase separates my components
Developing a new method
Developing a new method Choose the best column: stationary phase Consult colleague Search for Literature Wish to see a chromatogram how well the stationary phase separates my components Consult databases Retention indices Chromatogram libraries
Chromatogram databases on the web Agilent/Chrompack/J&W: http://en.informer.com/scanview/8.4/ Restek: http://www.restek.com/chromatogram/search/ Phenomenex: https://www.phenomenex.com/application Supelco/Sigma: http://www.sigmaaldrich.com/analytical-chromatography/applicationssearch.html?gclid=cjwkcajwro_mbrbxeiwayjndlknkdvr6wbzikx7a7iuquzs5e8fixl6qeheeg 34nKR--xxSK6FIYLxoCAVQQAvD_BwE SGE/Trajan: https://www.trajanscimed.com/collections/product-literature-analytical Macherey-Nagel: http://www.mnnet.com/default.aspx?alias=www.mn-net.com/apps
Using databases: Chromatograms Hydrogen sulfide Enter name here, for instance hydrogen sulfide
Sulfur components on Rxi-1ms Information includes Column dimensions GC-Conditions Peak identification and ret. time Download as PDF file Search options include: Component name Cass nrs Synonyms Matrix Component groups Method nrs (EPA, ASTM..)
Developing a new method Choose the best column: stationary phase Consult colleague Search for Literature Wish to see a chromatogram how well the stationary phase separates my components Consult databases Retention indices Chromatogram libraries Computer Aided Modelling
Modeling GC is very interesting for modeling because there are only a limiting number of parameters Selectivity Stationary phase type Impact of temperature Retention Film thickness Column diameter and length Temperature Carrier gas velocity (ID, length, type of gas, temperature, outlet pressure)
2 situations Changing an EXISTING method Faster, other gas, other column dimension, vacuum detector No change of stationary phase Developing a NEW method Select the MOST SELECTIVE stationary phase OPTIMIZE chromatographic conditions
How Can a Computer Help? Full Empirical Modeling of a Capillary Separation Method Translation and Pneumatic Calculations Predict separation metrics under a given set of conditions Iteratively optimize for the best separation Method Development Predict GC pneumatic parameters Translate existing methods Method Translation
2 situations Changing an EXISTING method Faster, other gas, other column dimension, vacuum detector No change of stationary phase Developing a NEW method Select the MOST SELECTIVE stationary phase OPTIMIZE chromatographic conditions
Biggest challenge in GC modeling Calculating the retention time in temperature programmed mode When a component travels through a column at a different temperature, the interactions will be different. Changing temperature program or flow: Some separations improve Some separations go worse or disappear Peak swapping
Separation Mechanism The Selectivity of a given chromatographic System, regarding the separation of two different Analytes, can be described by the Herrington Formula Vapour Pressure Term Solulibility Term
Peak swapping Some examples
Rtx-CL-Pesticides: peak swapping of pesticides
Rtx-5ms: the more complex the sample, the more risk separations will change 10ºC/min 13ºC/min 16ºC/min
Rtx-5ms: the more complex the sample, the more risk separations will change 10ºC/min 13ºC/min 16ºC/min
How to prevent this? Translate methods correctly, so the elution temperatures match up with the original method The method translator will help you to achieve this Changing any Parameter of your Chromatographic run needs to change the temperature program as well to achieve correct elution temperatures of every compound
EZGC Method translator and Flow-Calculator
Which Situations can benefit? When methods are changed, also the oven temperature program must be changed Optimizing the separation When a faster analysis is required (change of flow) When there is change of column dimensions Moving from a FID to a MS method (vacuum) Work with another carrier gas (N2 or H2) A combination from the above 22
2 situations Changing an EXISTING method Faster, other gas, other column dimension, vacuum detector No change of stationary phase Developing a NEW method Select the MOST SELECTIVE stationary phase OPTIMIZE chromatographic conditions
Select the most selective stationary phase This is not easy as interaction of component with stationary phase depends on: π - π interactions Van der Waals forces (Dipole, Londen) And these interactions are temperature dependent For a given component and given stationary phase the impact of temperature can be predicted EZGC
What is Pro EZGC chromatogram modeler? Pro EZGC modeler is a revolutionary GC method development tool But wait! It s free! Develop new methods Optimize existing methods Add analytes to methods Save time and money!
Pro EZGC The Pro EZGC chromatogram modeler, introduced in 2016 Is a free to use web application Input : a list of target compounds Output : a model chromatogram and suitable GC method conditions.. Column : Rtx -VMS, 30 m x 0.25 mm x 1.4 µm Carrier Gas : Helium, constant flow @ 1.68 ml/min Linear Vel. : 40.0 cm/sec Oven Temp : 35 C (hold 3.0 min) to 60 C @ 6.0 C/min to 225 C @ 20 C/min
Pro EZGC Adding new functionalities to the chromatogram modeler Full control over modeling GC conditions: you can immediately see what the impact is on the separation of YOUR components Separation shown on multiple stationary phases: select optimal phase Change the type of carrier gas (He, H2, N2, Ar/CH4) Change the flow (linear gas velocity) Change the oven conditions: temperatures and time Change the column dimension: select length, ID and film thickness Change from pressurized to vacuum detection
Pro EZGC : compound selection The first step is to select the compounds of interest Option 1: search by compound name or CAS# Option 2: search by stationary phase Enter a compound list here
The Initial Solution Select a solution A modeled chromatogram is obtained along with predicted separation metrics The solution can be used as is or alter it to specific needs
Rtx-VMS Rtx-1 Rxi-624Sil MS
Pro EZGC compound selection The first step is to select the compounds of interest Option 1: search by compound name or CAS# Option 2: search by stationary phase Select a phase Select a library
Choose Phase and Library
Pro EZGC compound selection The first step is to select the compounds of interest Option 1: search by compound name or CAS# Option 2: search by stationary phase Select a phase Select a library Select compounds / criticals
Option 2: Search by stationary phase: setting compound criticals Select all components that need to be modelled: Here are 6 components selected From the 6, there are 3 targeted that MUST resolve
Optimizing GC Conditions Helium, hydrogen, or nitrogen carrier All standard dimension columns can be modeled Flow control is set by the Results heading for Efficiency, Speed or full custom Oven program can be up to 5 ramps Refine oven program searches ramp rates
Choosing a different column dimension
Separation on 20m x 0.18mm Rxi-5Sil MS
Expanded view
Refine oven program Changing oven program
Original 15.5 min. First refinement 13 min. Second refinement 11 min. FIFTH refinement 7 min.
Changing oven temperature yourself 3.6 min.
Operate at a higher Flow 13 min. 6 min.
Fast GC Shorten retention times.. Short, narrow bore, thinner film columns Hydrogen carrier (or even faster) Fast temperature ramp rates Utilization of peak capacity What happens to predictive accuracy?
Example: Fast GC for Volatiles 6.2 min.
How well does the fast model align with real result? Modeled Real
Sensitive components
Pro EZGC Features Best Chromatogram and on multiple stationary phases Select column dimensions. (Length, ID, df) Select impact of all temperature settings Select impact of gas control settings and type of gas Works with pressurized and vacuum detection systems No GC required No columns to be purchased No FTE required Fastest way to check out applications at minimal costs Its a100% free service, available in several languages
Pro EZGC WOW!! I don t have to think anymore..! No!
Pro EZGC Constraigns Only components that are in the database can be modelled Modeling is done on a series of stationary phases
1/3 Unique Restek phases 2/3 Generic phases
Pro EZGC Constraints Only components that are in the database can be modeled Modeling is done on a series of phases Start temperature needs to be set in relation with solvent BP Ideal injection is assumed Limited to liquid stationary phases Peaks are 100% Gaussian: overload / tailing is not modeled There maybe more selective phases available that are not in this database
Carriergas Sailing Regattas are a Separation Process as well Analytes Stationary liquid Separation Phase
Thank you for your attention