Comparison GC-Inlets for Simulated Distillation … performance of each inlet type for ASTM D2887, D7500 and D7169 analyses is examined with a focus on the operational parameters required

Gulf Coast Conference 20131

A Comparison of GC-Inlets for Simulated Distillation Analyses

David GrudoskiweMeasureItAlbany,CA

A Comparison of GC-Inlets for Simulated Distillation Analyses

2013 Gulf Coast Conference,Galveston Texas

Presented by

David Grudoski

Abstract:

Simulated Distillation Methods allow for the use of either Programmable Temperature or Cool-On-Column inlets.

The performance of each inlet type for ASTM D2887, D7500 and D7169 analyses is examined with a focus on the operational parameters required for quality analyses.

The Purpose of the GC Inlet in SimDis Analysis

The function of the inlet is to allow the introduction of a liquid sample to the column of the gas chromatograph.

Ideally the inlet provides a complete transfer of the injected sample to the column.

Principles to Keep in Mind

Daltons Law of Partial Pressures

Raoult’s Law

Bernoulli effect

The Joule-Thomson Effect

Raoult’s Law

Raoult's law—the partial pressure of a component in an ideal solution is equal to the vapor pressure of the pure component multiplied by its mole fraction

The important consequence of Raoult's law is that the vapor above a boiling mixture is enriched in the lower boiling component.

Bernoulli Effect

When the speed of horizontal flow through a fluid increases, the pressure decreases

A common example used to explain the Bernoulli effect is the flow of fluid through a pipe. If the fluid is moving uniformly through the pipe, then the only forces acting on the fluid are its own weight and the pressure of the fluid itself. Now, if the pipe narrows, the fluid must speed up, because the same amount of fluid is traveling through a smaller space. However, if the fluid is moving uniformly, and the weight has not changed, then the only way in which the fluid will move faster is if the pressure behind the fluid is greater than the pressure in front. Thus, the pressure must decrease as the speed increases.

*Info from www.wiseGeek.org

The Joule-Thomson Effect

The Joule-Thomson (JT) effect is a thermodynamic process that occurs when a fluid expands from high pressure to low pressure at constant enthalpy.

Such a process can be approximated in the real world by expanding a fluid from high pressure to low pressure across a valve. Under the right conditions, this can cause cooling of the fluid.

At room temperature, all gases except hydrogen,helium and neon cool upon expansion by the Joule–Thomson process.*

*Info from Cryogenic Society of America

The Practical Consequences

As the sample is ejected from the syringe needle into the inlet, the sample expands and cools due to the Bernouli effect and the Joule Thomson effect.

With a straight thru liner; the sample components that boil below the temperature of the inlet would distribute in the vapor phase according to Raoults Law and pass onto the column.

The liquid material remaining in the inlet would also vaporize over time also according to Raoults Law.

SimDis Methods: RequirementsHardware D2887

C3-C44D7500C7-C100

D7169C1-C110

Inlet SSL,PTV,COC PTV,COC PTV,COC

Cryo Optional Optional Required

Column 10m,0.53 mm3.0u380 max

10m,0.53 mm5 m,0.53 mm0.15u400/435 max

0.53 mm10m 0.15u5 m 0.15u400/435 max

Oven -20:35040:350

40:400 -20:425

Solvent Optional OptionalOften required

OptionalOften required

SimDis RequirementsSetup D2887 D7500 D7169

100 % Sample Elution

Complete Elution

Complete Elution

Not Required

Blank Yes Yes Yes

Calibration Yes Yes Yes

Reference Optional Optional Required for % Recovery Calc

Sample Yes Yes Yes

ASTM SimDis Requirements

Gulf Coast Conference 2013Page 11

Column starting temperatures below ambient will be required if samples with IBPs of less than 93°C (200°F) are to be analyzed.

The sample inlet system must be capable of operating continuously at a temperature equivalent to the maximum column temperature employed, or provide for on-column injection with some means of programming the entire column, including the point of sample introduction, up to the maximum temperature required.

Connection of the column to the sample inlet system must be such that no temperature below the column temperature exists.

Challenges For High Temperature SimDis


Neat injections are problematic.

Increasing Boiling Point usually results in increasing viscosity of the sample and often requires dilution with a solvent.

Sample boiling ranges can be narrow or very broad with tailing distributions



Cross contamination of samples and solvent can occur if the syringe is not completely washed of sample residue

Any region of low or no flow in the inlet stream can deposit high boiling components which can subsequently elute either as peaks or bleed. Resulting in poor quality blanks and “memory effects”



Cold spots in the injection flow path can result in “memory effects” of the inlet where sample residuals from prior runs elute in later injections, especially for samples diluted in a solvent

Back diffusion from the split vent line and or purge vent line can also appear in analyses, especially when operating at high oven and inlet temperatures

Inlets used for Simulated Distillation

Split/Splitless (SSL)

Cool-On-Column (COC)

Programmed Temperature Vaporizing (PTV)

Multi-Mode Inlet (MMI)

Cold/Hot Split

Cold/Hot Splitless

Direct Injection (COC)

Solvent Vent

COC Advantages/Challenges

Advantages

Minimal discrimination of light ends

Challenges:

Injection reproducability

Retention Gap/Column Connection Union

Bleed of High Boiling material from Retention Gap


COC Injection Port

COC Flow Diagram

COC Inlet


COC Inlet


COC Inlet (Neat Injection)


Carbon # % Conc Difference Mean REL STDEV Run 1 Run 2 Run 3 Run 4

C7 8 ‐1.6 6.388 7.1% 5.712 6.557 6.679 6.604

C8 8 ‐1.1 6.870 4.4% 6.421 6.980 7.057 7.023

C9 8 ‐0.7 7.299 2.5% 7.028 7.358 7.402 7.408

C10 8 ‐0.5 7.529 1.0% 7.414 7.548 7.571 7.584

C11 4 ‐0.3 3.714 0.7% 3.744 3.728 3.692 3.694

C12 8 0.3 8.267 0.8% 8.367 8.224 8.226 8.248

C13 8 0.4 8.396 1.3% 8.558 8.337 8.333 8.356

C14 8 0.5 8.514 1.5% 8.701 8.450 8.443 8.462

C15 8 0.6 8.625 1.6% 8.826 8.567 8.545 8.563

C16 8 0.6 8.619 1.6% 8.829 8.562 8.532 8.551

C17 8 0.6 8.648 1.7% 8.865 8.606 8.555 8.565

C18 8 0.5 8.521 1.6% 8.721 8.498 8.439 8.425

C20 8 0.6 8.610 1.6% 8.813 8.585 8.526 8.517

PTV Advantages/Challenges

Advantages

Minimal discrimination of light ends

Rapid Heating and Cooling of Inlet-Reduces Cycle Time

Self Cleaning Inlet

Challenges:

Injection Volume limits

Memory effects from vent/purge lines


PTV Inlet (circa 1990)

Conventional vaporizing injectors are designed with high mass injector bodies and heating blocks to control temperature for large volume inserts.

These inlets change temperature slowly, contributing to their temperaturestability.

PTV Inlet (modern era)

Modern vaporizing injectors are designed with low mass injector bodies which allow very rapid heating and cooling of the inlet and permit selective vaporization of the sample in the body of the inlet liner.

This allows a pre-separation of the sample prior to introduction to the GC column which can result in a more efficient transfer of the sample to the GC column.

PTV Inlet


Split LineCapillary Column

Insert(vaporization Chamber)

Glass Wool / Packing

Carrier Gas

Heating Coil

Seal

Septum PurgeSeptum

Cooling Gas

Cooling Gas

PTV Inlet


PTV Inlet


PTV Inlet



C7 8 ‐1.3 6.664 1.3% 6.587 6.594 6.730 6.743

C8 8 ‐0.9 7.122 0.8% 7.073 7.070 7.166 7.180

C9 8 ‐0.5 7.468 0.3% 7.455 7.444 7.474 7.499

C10 8 ‐0.4 7.611 0.2% 7.617 7.606 7.595 7.625

C11 4 0.1 4.115 0.3% 4.129 4.123 4.096 4.111

C12 8 0.1 8.110 0.2% 8.128 8.123 8.084 8.104

C13 8 0.2 8.206 0.2% 8.220 8.219 8.184 8.203

C14 8 0.3 8.310 0.3% 8.323 8.343 8.276 8.299

C15 8 0.4 8.385 0.2% 8.401 8.402 8.363 8.375

C16 8 0.5 8.453 0.3% 8.476 8.466 8.435 8.435

C17 8 0.5 8.472 0.2% 8.475 8.474 8.494 8.444

C18 8 0.4 8.442 0.3% 8.452 8.441 8.464 8.411

C20 8 0.6 8.643 0.6% 8.666 8.695 8.639 8.572

MMI Advantages/Challenges

Advantages

Most versatile for injection and sample type

Rapid Heating and Cooling of Inlet-Reduces Cycle Time

Self Cleaning Inlet

Challenges:

Parameter setpoints can be complex to set

Injection Volume limits

Memory effects from vent/purge lines


Agilent Multi Mode Inlet

Operational Modes:

Cold/Hot Split

Cold/Hot Splitless

Direct Injection (COC)

Solvent Vent

MMI Schematic

MMI Parameters

Operational Mode: Split,

Cold Splitless,

Hot Splitless, Solvent Vent, Direct

Injection Volume

Septum Purge

Purge Vent Time

MMI Temperature Profile

MMI Inlet Liners


Single Taper with Glass Wool

Straight Through Narrow ID

MMI Cool-on-Column Inlet Adapter

MMI Inlet (Split Mode 4.5% Solution)



C7 8 ‐2.3 5.722 0.2% 5.734 5.723 5.721 5.709

C8 8 ‐1.5 6.512 0.2% 6.524 6.505 6.516 6.501

C9 8 ‐0.9 7.112 0.1% 7.122 7.108 7.117 7.102

C10 8 ‐0.6 7.449 0.1% 7.448 7.453 7.454 7.441

C11 4 ‐0.1 3.929 0.1% 3.927 3.930 3.931 3.926

C12 8 0.3 8.305 0.0% 8.304 8.306 8.302 8.308

C13 8 0.5 8.483 0.0% 8.481 8.482 8.481 8.489

C14 8 0.6 8.639 0.0% 8.637 8.639 8.635 8.644

C15 8 0.7 8.734 0.0% 8.731 8.734 8.733 8.736

C16 8 0.8 8.786 0.0% 8.782 8.788 8.784 8.790

C17 8 0.8 8.806 0.1% 8.806 8.808 8.799 8.812

C18 8 0.7 8.710 0.1% 8.704 8.711 8.709 8.716

C20 8 0.8 8.814 0.1% 8.799 8.813 8.817 8.826

MMI Split Mode 70:50:150:200:430 4:1 Split

MMI Inlet (Hot Splitless Mode)


Carbon # % Conc Difference Mean %REL STDEV Run 1 Run 2 Run 3 Run 4

C7 8 ‐2.3 5.653 0.1% 5.664 5.651 5.652 5.645C8 8 ‐1.6 6.425 0.1% 6.432 6.420 6.424 6.422C9 8 ‐1.0 7.036 0.0% 7.038 7.031 7.038 7.036C10 8 ‐0.6 7.411 0.0% 7.410 7.408 7.411 7.415C11 4 ‐0.3 3.729 0.0% 3.729 3.728 3.731 3.730C12 8 0.4 8.352 0.0% 8.348 8.351 8.352 8.356C13 8 0.5 8.538 0.0% 8.534 8.540 8.539 8.540C14 8 0.7 8.688 0.0% 8.684 8.690 8.689 8.689C15 8 0.8 8.830 0.0% 8.826 8.831 8.830 8.832C16 8 0.8 8.846 0.0% 8.842 8.848 8.846 8.847C17 8 0.9 8.889 0.0% 8.887 8.892 8.888 8.890C18 8 0.8 8.752 0.1% 8.758 8.752 8.746 8.752C20 8 0.9 8.852 0.1% 8.847 8.858 8.855 8.849

Hot Splitless Mode 150:0 min:720:380 2.5ml purge flow 0.5 min 0.1ul

Inlets Compared (Peak Area %)


Means ComparedCarbon # PTV COC MMI Split MMI Hot Splitless

C7 6.66 6.39 5.72 5.65

C8 7.12 6.87 6.51 6.42

C9 7.47 7.30 7.11 7.04

C10 7.61 7.53 7.45 7.41

C11 4.11 3.71 3.93 3.73

C12 8.11 8.27 8.31 8.35

C13 8.21 8.40 8.48 8.54

C14 8.31 8.51 8.64 8.69

C15 8.39 8.63 8.73 8.83

C16 8.45 8.62 8.79 8.85

C17 8.47 8.65 8.81 8.89

C18 8.44 8.52 8.71 8.75

C20 8.64 8.61 8.81 8.85

Inlets Compared (Relative Standard Deviation)


Relative Standard DeviationCarbon # PTV COC MMI Split MMI Hot Splitless

C7 0.01 0.07 0.00 0.00

C8 0.01 0.04 0.00 0.00

C9 0.00 0.02 0.00 0.00

C10 0.00 0.01 0.00 0.00

C11 0.00 0.01 0.00 0.00

C12 0.00 0.01 0.00 0.00

C13 0.00 0.01 0.00 0.00

C14 0.00 0.01 0.00 0.00

C15 0.00 0.02 0.00 0.00

C16 0.00 0.02 0.00 0.00

C17 0.00 0.02 0.00 0.00

C18 0.00 0.02 0.00 0.00

C20 0.01 0.02 0.00 0.00

Agilent SimDis Calculation


Agilent SimDis Calculation


Agilent SimDis Report


MMI Inlet SimDis Yield % Off


Yield % Mean %Rel STDEV Run 1 Run 2 Run 3 Run 4IBP: 0.5% 207.0 0.0% 207 207 207 2075.00% 210.0 0.0% 210 210 210 21010.00% 258.0 0.0% 258 258 258 25815.00% 302.5 0.2% 303 302 302 30320.00% 343.0 0.0% 343 343 343 34325.00% 345.5 0.2% 346 345 345 34630.00% 385.8 0.1% 386 385 386 38635.00% 421.0 0.0% 421 421 421 42140.00% 454.3 0.1% 454 454 454 45545.00% 456.0 0.0% 456 456 456 45650.00% 487.0 0.0% 487 487 487 48755.00% 489.0 0.0% 489 489 489 48960.00% 519.0 0.0% 519 519 519 51965.00% 521.5 0.2% 521 521 521 52370.00% 548.0 0.0% 548 548 548 54875.00% 575.0 0.0% 575 575 575 57580.00% 576.0 0.0% 576 576 576 57685.00% 600.0 0.0% 600 600 600 60090.00% 602.0 0.0% 602 602 602 60295.00% 650.8 0.1% 651 650 651 651

FBP: 99.5% 652.8 0.1% 653 652 653 653

SimDis Yield % Off Temp Compared (Mean Temp)


Yield % PTV Mean COC Mean MMI MeanIBP: 0.5% 206.5 207.5 207.05.00% 209.5 210.0 210.010.00% 256.8 258.3 258.015.00% 301.5 301.8 302.520.00% 303.5 314.0 343.025.00% 344.5 345.3 345.530.00% 384.0 384.8 385.835.00% 419.5 420.3 421.040.00% 421.5 430.0 454.345.00% 455.5 455.8 456.050.00% 486.3 485.8 487.055.00% 488.0 488.5 489.060.00% 517.5 517.8 519.065.00% 519.5 525.5 521.570.00% 547.5 547.5 548.075.00% 573.8 573.0 575.080.00% 576.0 576.0 576.085.00% 600.0 599.5 600.090.00% 602.0 601.5 602.095.00% 650.5 650.3 650.8

FBP: 99.5% 657.8 652.3 652.8

SimDis Yield % Off Temp Compared (% Rel Std Dev)


Yield % PTV %Rel StDev COC %Rel StDev MMI %Rel StDevIBP: 0.5% 0.3% 0.3% 0.0%5.00% 0.3% 0.0% 0.0%10.00% 0.4% 0.2% 0.0%15.00% 0.2% 0.2% 0.2%20.00% 0.2% 6.2% 0.0%25.00% 0.2% 0.1% 0.2%30.00% 0.0% 0.1% 0.1%35.00% 0.1% 0.1% 0.0%40.00% 0.1% 3.7% 0.1%45.00% 0.1% 0.1% 0.0%50.00% 0.1% 0.1% 0.0%55.00% 0.0% 0.1% 0.0%60.00% 0.1% 0.1% 0.0%65.00% 0.1% 2.2% 0.2%70.00% 0.1% 0.1% 0.0%75.00% 0.1% 0.0% 0.0%80.00% 0.0% 0.1% 0.0%85.00% 0.0% 0.1% 0.0%90.00% 0.0% 0.1% 0.0%95.00% 0.1% 0.1% 0.1%

FBP: 99.5% 0.3% 0.1% 0.1%

Summary and Conclusion

Each of the inlets discussed have advantages for specific sample types.

All can reliably perform SimDis Analyses


Comparison GC-Inlets for Simulated Distillation … performance of each inlet type for ASTM D2887, D7500 and D7169 analyses is examined with a focus on the operational parameters required

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