A Dual Channel Pre-column Backflush System · 2016. 9. 2. · – Primary use = post-column splitter to two detectors – Backflush – Can be used in other configurations e.g., pre,

Gulf Coast Conference 2012

Page 1

A Dual Channel Pre-column Backflush System

Roger L. Firor Agilent Technologies 2850 Centerville Rd Wilmington, DE USA

AUX

MMI FID 2

FID 1

Pre-column

Column 2

restrictor

In oven

Outline

• Introduction to backflush • System configuration with CFT (Capillary Flow

Technology) • Software tools • Hardware configurations • Application examples • Advanced setups

Page 2


Why use Backflush ?

Those that need: • Retention time precision • Improved spectral quality • Longer lasting calibrations • Improved quantitation • Shorter analysis time • Increased column lifetime • Reduced source maintenance

Page 3


Pre-column Backflush

• Eliminate bake out times at end of runs • Dirty samples • Late eluting compounds of no analytical interest • Need to protect column from high boilers • Interest in maximizing lab throughput and minimizing

cost of operations • Compatible with GC and GC/MSD systems • Alternative for established methods

Page 4


Advantages of Pre-column Backflush

Backflush is carried out while analysis is occurring on the analytical column

Midpoint pressure control allows analytical column to run at desired flow while pre-column is backflushed

Use of an uncoated pre-column allows transfer of components at a relatively low temperature (i.e. 35 C) and faster backflushing of the heavier components

Sample matrix has little influence

Wide choice of pre-column and analytical column dimensions and phase ratios possible to meet specific application needs


Page 5

Backflush with Coated Pre-columns

Pre-columns with thin coating (i.e. 0.10 um to 0.25 um films) can be used

Provides finer control of compounds that are backflushed

Backflush times will be much longer typically

Backflush of heavy compounds remaining on the pre-column will take longer

Better inertness


Page 6

Use Flow Start with working method

Extract pertinent method information from method files

Select BF configuration

Set up and verify hardware

Install columns and test configuration

Screen standard on new configuration

Lock with recasted RTL calibration if RTL method

Pick last peak of interest using graphical tool, from which BF timing and conditions are recommended

Verify BF works

Fine tune BF conditions if necessary

Page 7


Principle Of Backflushing

S/SL Inlet

Capillary Flow Device

1 psi

75 psi

Detector(s)

Split Vent

During GC Run

After GC Run

S/SL Inlet

Capillary Flow Device

25 psi

3.8 psi

Detector(s)

Aux EPC Split Vent

Aux EPC

Page 8


Principle Of Backflushing

Concurrent During GC

Run S/SL Inlet

Backflush Device

1 psi

Appropriate column

Pressure maintained

Detector(s)

Aux EPC Split Vent

Page 9


Backflushing After Each Injection

Backflush 20 sec Flow




Column Inlet

End of/or during Run Flow

Backflushing removes heavy materials after each injection.

Page 10


AUX EPC

Pre-column

Purged Ultimate Union

Multimode Inlet Temperature programmed split

1.6 mL/min 2.0 mL/min

Analytical Column

140 mL/min

FID

Basic System Overview

Three Configurations and Two Modes of Backflush

Post-run Easiest to set up

Coated Pre-Column (split column) More set-up - Concurrent Faster Turn-Around-Time - Post Run

Uncoated Pre-Column More set up - Concurrent Even Faster Turn-Around-Time

Page 12


Pressure zeros should be set on the GC for the inlet and Aux channels before use

Post and Concurrent

BF Wizard Overview

• Software based tools to: – Guide end-user to a proposed BF configuration – Illustrate step-by step procedure to configure BF hardware /

plumbing – Develop a BF enabled method

• Automated BF development for > 8 peaks in a chromatogram

• Comparison mode for 3 ≤ # Peaks ≤ 8 • < 3 peaks in chromatogram is a manual process

Page 13


Backflush Method Setup

14 Gulf Coast Conference 2012

Backflush Method Setup


Backflush Setup


Page 16

Backflush Setup


Page 17

Backflush Setup


Page 18

Backflush Setup


Page 19

Backflush Setup


Page 20

Backflush Setup


Page 21

Backflush Setup


Page 22

Backflush Setup


Page 23

What Kind of Devices can be used for Backflushing?

Anything with an independent pressure or flow control

Purged Union

Purged Splitter

Deans Switch


PUU Purged Ultimate Union (Pressure Controlled Tee)

– Primary use = Backflush – Pre-column and post column configurations

• Inlet to one detector – Note: pre-column includes mid-column

– Pre-column configurations can be implemented with diff pump

– Recommended for GC and GC/MS systems


Effluent Splitters

• 2-way effluent splitter – Primary use = post-column splitter to two detectors – Backflush – Can be used in other configurations e.g., pre, mid, post-column

• Not best practice: must plug one port – Don't use just for BF, use if > 1 detector

• 3-Way effluent splitter

– Primary use = post-column splitter to three detectors – Backflush – Can be used in other configurations e.g., pre, mid, post-column

• Not best practice: must plug one port – Don't use just for BF, use if > 2 detectors



Page 27

Backflush with Purged Union: Polywax 500 Sample: C5-C18 plus PW500

C26, 10 min

C36, 14 min

C42, 16 min

2 m x 0.53 mm Uncoated retention gap

Pre-column Backflush of C5-C18 Mix After C14


Page 28

Retention time STD’s < 0.0019 min

1M x 0.32mm retention gap, 100M x 0.25mm x 0.50um DB-PETRO

C14

C12

Crude Oil Backflush with Coated 2 m x 0.32 mm x 0.10 um DB-1 Pre-column Conditions: Pre-column flow 1.6 ml/min, Analytical column flow 2.0 ml/min MMI: 250 °C(0.5 min) to 425 °C @ 200 °C/min Oven Program: 35 °C (4 min) to 200 °C (1 min) @ 2.0 °C/min Analytical column: 100m x 0.25mm x 0.5um DB-Petro

Backflush time: 4 min

Backflush time: 8 min

C10

C11

Page 29


2M x 0.32mm x 0.10um Pre-column: 12 Run Overlay of Crude Oil


Page 30

Single Channel Configuration

FID

He or H2

EPC1 P2

IN

Oven

Purged Union

30 m x 0.25 mm x 0.25 um HP-1

30 m x 0.25 mm x 0.50 um HP- INNOWax

Bleed

MMI

P1

restrictor


Improved stability at low flows

CFT Splitters Configured for Analytical and Pre-column Monitor Channels


Page 32

Two un-purged splitters are used

AUX

MMI FID 2

FID 1

Pre-column

Column 2

restrictor

In oven

CFT Splitter Configuration


Page 33

Pre-column in

Pressure source in

Pre-column monitor

Column 2

Light Crude: Backflush after C14 Monitor channel in red, 3 m x 0.32 mm x 0.25 um pre-column


Analytical column: 100m x 0.25mm x 0.5um DB-Petro

Iso-Paraffinic Kerosene


Analytical column: 100m x 0.25mm x 0.5um DB-Petro

Monitor channel in blue, 3 m x 0.32 mm x 0.10 um pre-column

Synthetic Iso-Paraffinic Kerosene

BF = 6 min BF=8 min


Analytical column: 100m x 0.25mm x 0.5um DB-Petro Monitor channel in red, 3 m x 0.32 mm x 0.10 um pre-column

SPK Sample Overlay of runs at 8 and 10 min backflush times


D3606 Parameters with Hydrogen Carrier

Oven: 80 °C isothermal

Column 1: 30 m x 0.25 mm x 0.25 um HP-1

Column 2: 30 m x 0.25 mm x 0.50 um HP-INNOWax

Column 1: 22.9 psig

Column 2: 15.0 psig

Backflush at 4.10 min


HP-1/INNOWax System

D3606 Parameters with Hydrogen Carrier

Oven: 65 °C isothermal

Column 1: 30 m x 0.25 mm x 0.25 um HP-1

Column 2: 50 m x 0.25 mm x 0.40 um CP-TCEP

Column 1: 26.8 psig

Column 2: 20.5 psig

Backflush at 4.00 min


HP-1/TCEP System

Column Setup for Backflush

Gulf Coast Conference 2012 40

HP-1/TCEP System for D3606

D3606


Benzene

Toluene

HP-1/INNOWax System, 80 °C

Overlay of Calibration Mix and Shell 89


HP-1/TCEP System for D3606 BF at 4.00 min

Overlay Calibration Mix with Shell 89


Benzene

Toluene

Column 1: 30 m x 0.25 mm x 0.25 um HP-1 Column 2: 50 m x 0.25 mm x 0.4 um TCEP

Calibration: HP-1/INNOWax System

y = 0.404x R² = 1

0

0.5

1

1.5

2

2.5

0 1 2 3 4 5 6

Benzene

y = 0.4214x R² = 1

0 1 2 3 4 5 6 7 8 9

0 5 10 15 20 25

Toluene

%LV %LV

Hydrogen carrier


Hydrogen Carrier, Isothermal at 80 °C

Run Sample Amt Benzene Vol %

Amt Toluene Vol %

1 Reference 0.82 5.31 2 Reference 0.85 5.31


Column Set

Column 1: 30 m x 0.25 mm x 0.25 um HP-1 Column 2: 30 m x 0.25 mm x 0.50 um HP-INNOWax

All runs are independent sample preps

Hydrogen Carrier, Isothermal at 65 °C

Run Sample Amt Benzene Vol %

Amt Toluene Vol %

1 Reference 0.86 5.58

2 Reference 0.87 5.40

1 Shell 89 1.03 5.12

2 Shell 89 1.02 5.25

3 Shell 89 1.06 5.27


Column Set

Column 1: 30 m x 0.25 mm x 0.25 um HP-1 Column 2: 50 m x 0.25 mm x 0.4 um TCEP

All runs are independent sample preps

Advanced Configurations for Backflush


Variable Split Bleed Saves The Day

Provides necessary bleed to allow pressure control solenoids to operate well (> 1 mL/min) Maintains low flow even during high-pressure backflush Uses normally unused pressure channel (EPC, Backpressure channel on PCM) Allows split flow to be turned OFF for leak checking Provides the opportunity to program bleed flow for custom applications

Using 2nd EPC for Bleed During Run

Set P3 < P2

2 mL/min independent of

P2

Purged Union Column 1 Column 2

Det

SV Trap

He supply

EPC1 P2

IN

Oven

IN

EPC2 P3

atmosphere 1/16” Swagelok tee

Page 49


Crude Oil GCxGC: Pre-column Backflush


Page 50

BF at 30 min, Oven programmed to 390 C

FID

PCM

FID

PCM

MMI

FID

Column 1

Column 2

PCM Micro Valve

PCM: Pressure control mode,

Modulator

AUX

Restrictor/ Pre-column

G3186B

Aux: Controls Column 1 in constant flow

21-25 ml/min typical

Summary

• CFT devices with an Aux pressure/flow source can be used for backflush applications • Relies on precise EPC midpoint pressure control

• Backflush can be concurrent while analytical column runs at constant flow

• Excellent thermal control since all parts are in the oven

• Heavy petroleum including crude oils can be routinely analyzed with complete protection of the high resolution capillary column

• The specific carbon number where backflush begins can be easily controlled and fine tuned

• Coated pre-columns offer additional control for precise compound cuts

•First or pre-column can be anything from short (2 m) retention gap to high res cap column

• Dual channel configurations allow direct monitoring of the first column

• Straight forward configurations for ASTM D3606


Documents

A Dual Channel Pre-column Backflush System · 2016. 9. 2. · – Primary use = post-column splitter to two detectors – Backflush – Can be used in other configurations e.g., pre,