Low Thermal Mass (LTM) GC Technology Revealed: A · PDF fileRoger L Firor Agilent Technologies Wilmington, DE Low Thermal Mass (LTM) GC Technology Revealed: A Practical Guide Page

Roger L Firor

Agilent Technologies

Wilmington, DE

Low Thermal Mass (LTM) GC

Technology Revealed: A Practical

Guide

Page 1

Gulf Coast Conference 2011


“LTM” (Low Thermal Mass) Technology (Patented)

Directly heat/cool fused silica GC columns

Page 2

LTM - Low Thermal Mass Technology

3

“Fast Temperature Ramps”

“Spec” 1800oC/min, Typical <400oC/min

Temperature Range 120 V Oven Fast Ramps Insert **

(°C) (°C/min) > 200 V, 15A > 200 V, 15A

50 to 70 75 120 120

70 to 115 45 95 120

115 to 175 40 65 110

175 to 300 30 45 80

300 to 450 20 35 65

* * Requires G2646-60500

LTM Cooldown Times (Standard Size)

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250

Time (sec)

Tem

p (

oC

) 2m LTM

5m LTM

10m LTM

7890 GC

“Fast Cool-Down”


LTM Column Module


Page 4

Lead

Torus Lead

FANS

Installed external to main GC oven

Connecting an LTM Column Module to Inlet and

Detector

• Option 1: Use CFT unions and deactivated fused silica leads

of same diameter as column

> Column module protected by retention gap tubing

> Users need to learn how to make CFT connections

• Option 2: Use module with long column leads

> Avoids use of unions

> 0.5 to 0.8 m of column is kept at elevated temperature


Page 5


Page 6

Module to Retention Gap Connection

Old New

2010: Valco Unions Unions Based on Capillary

Flow Technology (CFT)

Metal Ferrules Easy to use, do not loosen or leak

with oven cycling to 350 C

Metal Deactivation

Page 7


Transfer Line Assembly


Page 8

Heated column guide

Brackets attach to rails


Page 9

5 inch Column Module Installed on Transfer line

2011: LTM II

LTM Integrated w/ 7890 GC

- Hardware

- Firmware

- Software

Page 10


LTM II: Electronics/Firmware Integration

LTM PCB – Direct digital communication

w/ 7890 GC FW/UI:

- PCB has “GC” performance/reliability

- Improved thermal control (now digital).

Temperature control/display

- Confirms cable connections

- Diagnostics, thermal fault detection

- Added “GC” Press/Flow compensations

multi-piece columns (knows temp)

- Local control via 7890 keyboard

- LTM integrated into GC, GC/MS SW platforms

Page 11


LTM Series II IN Segment Out Segment Segment 2

GC Oven GC Oven MSD

Column Segment

Configuring an LTM II Module in ChemStation

12


GC Oven is set isothermal at a temperature at or close to maximum

LTM module programmed temperature

What are the Best Uses for LTM Technology?

• Speed up an analysis where overall throughput is important

> Simulated Distillation

> Total Petroleum Hydrocarbons

> Solvent analysis

• Multi-dimensional separations where an independent oven is

needed to operate under a different temperature program

compared to the main GC oven

>Residual sulfur in diesel

> Fuel Ethanol

> GC X GC


Page 13

The LTM Advantage


Page 14

• Total Cycle time for an analysis can be cut by a factor of

three or more (compared to same columns in an air oven)

• Single or dual column configurations (5 inch format)

• Dual column configurations allow simultaneous injection

• With dual column modules, two different phases (i.e. 624 and Wax) can be used

• Temperature programs for the two column modules are independent

Four modules possible with 3 inch format

• Simultaneous start times are required, however, end times can vary

• Compatible with CFT devices for splitting - two columns, or for backflush

• Powerful tool when combined with a CFT Deans switch

Setting Column Flow with an LTM Module (First

Generation)


Page 15

•The 7890A or 6890 Series GC’s did not have knowledge of LTM column

temperature

•Constant flow mode could not be set from the GC keypad or software

•Options for setting flow in an LTM Module - constant pressure

- ramped flow

For approximate constant flow-

- construct a flow ramp

- manually measure flow at staring and final temperature- input flow ramp

Setting Column Flow with an LTM Module (Second

Generation: LTM II)


Page 16

•The 7890A GC has knowledge of LTM column module temperature

•Constant flow mode integrated

•Options for setting flow in an LTM II Module > constant pressure

> constant flow

> ramped flow

•LTM II control completely integrated in GC ChemStation

•LTM II parameters can also be set from the 7890A keypad


Page 17

*Maximum program rate for 120V 7890A is 30 C/min from 35 °C to 240 °C

** Maximum program rate for 220V 7890A is 45 C/min from 35 °C to 240 °C

Comparison of Cycle Times: Conventional Air Bath vs. LTM

Heating Column Program Cool Down Cycle

Time

7890A (120V) 30M x 0.53mm x

3.0um DB624

40 C(20 min) to 240

C (20 min) @ 10

C/min

6 min 50 sec with

3 min oven equil. 67 min

7890A (120V) 7M x 0.25mm x

1.4um DB624

35 C (5 min) to 240

C (5 min) @ 30

C/min *

8 min 25 sec

with 3 min oven

equil.

25 min

15 sec

7890A

(220V)

7M x 0.25mm x

1.4um DB624

35 C (5 min) to

240 C (5 min) @ 45

C/min **

8 min with 3 min

oven equil. 22 min

30 sec

LTM (Fast) 7M x 0.25mm x

1.4um DB624

35 C (5 min) to 240

C (5 min) @ 60

C/min

1 min 45 sec (one

module system)

15 min

10 sec

LTM (Faster) 7M x 0.25mm x

1.4um DB624

35 C (5 min) to 240

C (3 min) @ 100

C/min

1 min 45 sec (one

module system) 11 min

45 sec

LTM (Fastest) 7M x 0.25mm x

1.4um DB624

35 C (4 min) to 240

C (3 min) @120

C/min

1 min 45 sec (one

module system) 10 min

30 sec


Page 18

Fast Chromatography

• Users typically choose columns that are longer than needed

for a given application

• Optimal oven program rates will be around 10 °C/void time

• Consider column flow rates that are 2 to 3 times optimum

• When translating a method from air-bath to LTM:

- consider changing both column ID and length

- use method translation software for guidance

• Rarely will practical LTM program rates exceed 400 °C/min


Page 19

Method Translate: Long to Short Column of Same

Diameter [column rows]

Flow Rate Column ID 10M 5M 4M

ml/min um (°C/min) (°C/min) (°C/min)

12 530 15 31 (2X) 40 (2.6X)

6 320 15 34 (2X) 44 (3X)

3 250 15 35 (2X) 45 (3X)

2 180 15 34 (2X) 50 (3X)


Page 20

Simplest Calculator: Agilent Pressure/Flow Typically used to find inlet pressure and/or flows

Lengths and diameters are found by iteration


Page 21

Agilent Method Translator Find conditions to get same elution order and precisely scale method to new speed or

new outlet pressure

New inlet pressure

New flow

Speed up factor

Constant phase ratio

Translation from 10M to 5M: D2887


Page 22

Column ID and Phase ratio maintained

Translation from 530 to 320


Page 23

320 column available with

1.50um film – close enough

Phase ratio maintained


Page 24

Translation to LTM: D2887 SimDis 530u to 320u column

Interfacing LTM II to a Deans Switch


Page 25

Deans Switch Calculator

Primary column: 1.3 ml/min, LTM: 2.5 ml/min

September 22, 2011 26

LTM Series II/ Deans Switch/5975C

System Diagram: LTM ll/Deans/FID-MSD

Primary column

30 m x 0.25 mm x 0.25 um DB5ms

2 1

3 NO

NC

Split

Inlet 5975C

MSD

LTM II

FID restrictor

PCM

Deans Switch

27


7 m x 0.25 mm x 0.25 um

HP-INNOWax

System Diagram: LTM ll/Deans/FID-FID

Primary column

2 1

3 NO

NC

Split

Inlet

LTM II

FID restrictor

PCM

Deans Switch

FID

28


4,6-Dimethyl dibenzothiophene in Road Diesel


Page 29

FID

SIM

TIC

7.2 ppm

Oven Programs

Primary: 80 °C (0) to 340 °C (5) @ 10 °C/min

LTM II: 50 °C (3) to 240 °C (5) @ 8 °C/min Ovens offset by 30° C

10.6 ppb 4,6-Dimethy dibenzothiophene


Page 30

SIM

Standard

1.8 ppm of 4,6-Dimethyl dibenzothiophene in

Marine Diesel


Page 31

FID

SIM

TIC

Calibration


Page 32

y = 125764x - 17928 R² = 0.9995

0

200000

400000

600000

800000

1000000

1200000

1400000

0 2 4 6 8 10 12

4,6-Dimethyldibenzothiophene

y = 91849x + 806.33 R² = 0.9999

0

20000

40000

60000

80000

100000

120000

0 0.2 0.4 0.6 0.8 1 1.2

ppm

ppm

Fuel Ethanol


Page 33

1 2

3 4

5 6

EtOH

1. Butane

2. Acetaldehyde

3. Iso-pentane

4. Pentane

5. 2-Pentene

6. Methanol

Methanol level is 0.01%

Primary oven: 50 °C (5 min) to 280 °C (5 min) @ 20 °C/min

LTM: 30 °C (4 min) to 240 °C (5 min) @ 8 °C/min

Cut: 1.80 min to 2.00 min

Primary oven: 30 m x 0.25 mm x 0.25 um DB-5ms

LTM: 7 m x 0.25 mm x 0.25 um INNOwax

Ovens offset by 20 °C

LTM II/Deans Switch for Analysis of Natural Oils


Page 34

Geranium, cuts at: 8.25 to 8.38

(linalool), 9.3 to 9.5 Methone),

10.0 to 10.9 ( citronellyl formate,

B-citronellol, nerol)

1

2

3

4

5

6

Primary column: 30 m x 0.25 mm x 0.25 um DB5ms

LTM II column: 30 m x 0.25 mm Cyclodex

Primary:70 °C (1) to 280 °C (17) @ 10 °C/min

LTM II: 75 °C (7) to 130 °C (5) @ 2 °C/min

Oven Programs

1. Linalool

2. Methone

3. Citronellolyl Formate

4. Citronellol

5. Cital

6. Nerol

Fast GC Applications


Page 35

Parameters: Hydrocarbon Oil Index


Page 36

Injection 1 µL, splitless (0.4 min purge delay), 350°C

Inlet liner split/splitless P/N 5183 - 4647

(bottom taper, glass wool near top, 4 mm i.d., )

Carrier gas 9 mL/min He constant flow

LTM Column 10 m x 0.32 mm i.d. x 0.1 µm DB-5HT

LTM Retention gap leads 0.5 m x 0.32 mm ID on inlet and detector sides

Standard oven program 40°C (0.5 min), 340°C (0.5 min) @ 15°C/min

[total run time = 21 min]

GC oven temp when using LTM II 340°C isothermal (3 min)

LTM II oven program 40°C (0.5 min), 200°C/min 240°C,

100°C/min 340°C (0.5 min) [total time = 3min]

C 10 to C40 alkane test mix: 0.001 min SD or 0.03% RSD


Page 37

Motor oil

Diesel

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.20 2.40 2.60 2.80 0

500000

1000000

1500000

2000000

2500000

3000000

3500000

4000000

4500000

Time (min)

Re

sp

on

se

400 mg/L Calibration Sample of Diesel

Plus Motor Oil


Page 38

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 4500000

Resp

on

se

0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00

500000 1000000 1500000 2000000 2500000 3000000 3500000 4000000 4500000

Time (min)

Resp

on

se

LTM, 3 min run

Standard, 21 min run

Comparison of Sensitivity Gain from Standard

Oven Program to Fast LTM Program

Diesel plus motor oil standard at 400 mg/L.

D2887 SimDis


Page 39

5 m x 0.32 mm x 0.5 um DB1

LTM Module: 35°C to 350°C (30 s) @ 100°C/min

Multimode inlet: 325°C (0 min) to 355°C (2 min) @ 200°C/min

Constant Flow: 12 ml/min

Split: 20 to 1

7890A oven: 300°C

C5 to C40 Calibration in under 3 min.

RGO


Page 40

PW 500: LTM II System

0 1 2 3 4 5 6 7 8

Column: 5M x 0.53mm x 0.15um DB-HT SimDis

LTM Temp Program: 40°C (0 sec) to 400°C (30 sec) @ 50°C/min

7890A Oven: 325°C Isothermal

7890A Carrier: He, constant flow

Injection: 2 ul of PW500 in toluene

PTV: 210°C (0 min) to 400°C (2 min) @ 300°C/min

C20 C70

GCxGC: Dual LTM II System


Page 41

PCM: Pressure control mode,

S/S inlet:: constant flow mode

LTM columns in constant flow

Three Independent temperature programs possible

FID FID FID

Column 2

S/S Inlet

Column 1

PCM Micro Valve Modulator

S/S Inlet

Column 1


S/S Inlet

Column 1


FID FID FID

Column 3

FID FID LTM

FID FID LTM

FID FID

Splitter LTM = Low Thermal Mass

Dual LTM: DB17HT and INNOwax


Page 42

DB17HT

INNOwax

40 °C (0 min) to 200 °C @ 3 °C/min

5 m x 0.25 mm x 0.15 um

30 °C (5 min) to 240 °C @ 2 °C/min

5 m x 0.25 mm x 0.15 um

Paraffin/aromatic mix

•Faster method development

•Complimentary results

depending on application

•Allows wider range of columns

(phase ratio’s) to be used

•Greater separation power for

complex materials

LTM Series II

• System part # : G6680A, 5 inch format with 2 power supplies

• 7890A firmware requirement: A.01.12.1 or greater

• GC ChemStation: B.04.03 DSP1, includes LTM II control

software

• MSD ChemStation: E.02.02


43

Summary

• LTM series II incorporates a number of new features including full control

integrated in ChemStation, and operation in true constant flow mode that

assists the analyst with development of new methods. This is especially true

with more complex configurations involving the Deans switch and 5975C

MSD.

• The use of two independent ovens gives the analyst flexibility to optimize

analysis by using unique oven programs with offset temperatures.

• In many applications, analysis time will also be shorter since only

compounds of interest are cut to the chiral column.

• High ramp rates and rapid cool down give faster overall cycle times.

• Method translation software should be used when developing a fast

method.


44

Documents

Low Thermal Mass (LTM) GC Technology Revealed: A · PDF fileRoger L Firor Agilent Technologies Wilmington, DE Low Thermal Mass (LTM) GC Technology Revealed: A Practical Guide Page