Applications of Gas Chromatography with Headspace Autosampler

Background: GC vs. HS-GC

• Two separate calibration curves (C,D) were generated in

the laboratory using liquid samples of 10, 40, 50, 65, 90,

and 100 % (v/v) ethanol/water using GC.

• Sample preparation was improved between analysis as

shown on each calibration

Proposed HS-GC-Method

A method proposed by Shan et al., (2011) using a HS-GC with

a FID detector will be tested during the summer to evaluate

SCFA.

Headspace Explanation

• Partition coefficient: K=Cs/Cg

• Phase Ratio: B=Vg/Vs

• Headspace Concentration: Cg=Co/(K+B)

• As T goes up, K goes down

• Activity coefficient: Pi=Po x Yi x Xs(i)

• Adding salts to EtOH/H

O samples

EtOH/H

O Calibration Curves

Applications of Gas Chromatography with Headspace Autosampler

Paul Maricocchi

Advisors: Dr. Erick Vasquez and Dr. Yvonne Sun

Introduction

Gas chromatography (GC) is a separation

technique for volatile compounds that involves the

vaporization of a sample through an injector.

Then, the sample is carried by a gas moving

through a stationary phase (column) packed with

a gel or a solid until reaching a detector. The

CME Department recently acquired a GC system

with exchangeable detectors: Thermal

conductivity detector (TCD) and flame ionization

detector (FID). To enhance interdisciplinary

collaboration across Units and Departments

within the University of Dayton, this work seeks to

develop GC and Headspace-GC (HS-GC)

analytical methods for use both in the classroom

and in research.

Objectives

• To understand the variables manipulated in

GC and HS-GC and apply this knowledge to

developing characterization methods

• To generate a characterization method to

determine the concentration of ethanol in

aqueous mixtures obtained from a distillation

process

Methods

An extensive literature review has been

conducted through Journal articles, books, and

webinars before starting with the Summer

Undergraduate Research Experience(SURE)

program with the SoE this summer.

Equipment

• Thermo Scientific GC w/TCD

and FID detector

• Autosampler (Triplus RSH)

• Capillary Column

[TG-BOND Q+]01mm)]

• HS and GC vials

Using HS-GC Quantitatively

• Sample volume: Vs=Ve x (Fcol/Fcol+Fs)

• Injection time: Ti=(Vsyr/Fcol+Fs)x(Pi/Pa)

• This combination allows sample concentrations

determination

Future Applications

• Analyze ethanol and water samples obtained

from the Unit Operations Laboratory.

• Characterize the efficiency of GC analysis of

EtOH/H

O/oil samples vs. using HS-GC for

ternary mixtures

• Characterize SCFA (short chain fatty acid)

content in Listeria metabolites present in mice

feces with the SURE program in the SoE during

this summer

Acknowledgements

We are grateful to the Chemical and Materials

Engineering Department for supporting this work and

the 2018 SURE SoE program.

Thermo Scientific GC

And Autosampler

Selected References

1. Kolb, B., & Ettre, L. S. (2006). Static headspace-gas chromatography:

theory and practice. John Wiley & Sons.

2. Shan, X., Tiscione, N. B., Alford, I., & Yeatman, D. T. (2011). A study of

blood alcohol stability in forensic antemortem blood samples. Forensic

science international, 211(1-3), 47-50.

3. Tipler, Andrew. “An Introduction to Headspace Sampling in Gas

Chromatography Fundamentals and Theory.” (2013)

4. Tiscione, N. B., Alford, I., Yeatman, D. T., & Shan, X. (2011). Ethanol

analysis by headspace gas chromatography with simultaneous flame-

ionization and mass spectrometry detection. Journal of analytical

toxicology, 35(7), 501-511..

Distillation Column

Perfume Chromatographs obtained using a direction injection

GC (A) method and a Headspace sampling technique (B).

(Tipler, 2013)

Headspace sampling: The more volatile compounds are

extracted from the sample. For example:

Results and Discussion