spme

Topics: Gas chromatography, Chromatography, Benzene Pages: 16 (2572 words) Published: May 28, 2014
EXPERIMENT 4
ANALYSIS OF HYDROCARBON IN COMMON FUELS BY SOLID-PHASE
MICROEXTRACTION (SPME) AND GAS CHROMATOGRAPHY-MASS
SPECTROMETRY (GC-MS)

Abstract

In the analysis the solid-phase microextraction (SPME) and capillary gas chromatography/mass spectrometry (GC/MS) was developed for the identification of volatile compounds (hydrocarbon) in fuel. The samples was used is (kerosene, diesel, thinner and petrol) and one unknown. After the analyte was extracted by SPME in 20min, it directly injected to the GCMS with desorption time 80sec.After the analysis was done, the result was stated at table 4.1, the unknown was identified as a petrol because the hydrocarbon presence in the unknown is the same with the hydrocarbon compound in the petrol sample. Aromatic hydrocarbon was presence in both sample petrol and unknown. Alkanes hydrocarbon was presence in other sample.

Objective

The objectives of this experiment are to perform sample preparation by SPME and to identify the components of hydrocarbon in common fuel using SPME-GC-MS.

Introduction

Solid phase microextraction, a simple, effective adsorption/desorption technique, eliminates the need for solvents or complicated apparatus for concentrating volatile or nonvolatile compounds in liquid samples or headspace. SPME is compatible with analyte separation/detection by gas chromatography or HPLC, and provides linear results for wide concentrations of analytes. By controlling the polarity and thickness of the coating on the fiber, maintaining consistent sampling time, and adjusting several other extraction parameters, an analyst can ensure highly consistent, quantifiable results from low concentrations of analytes.

Analyses of volatile or semivolatile organic environmental pollutants,flavor or fragrance components, and many other samples usually begin with concentrating the analytes of interest through liquid-liquid extraction, purge-and-trap, headspace, or various other techniques. These procedures typically require excessive time, complicated equipment, and/or extravagant use of organic solvents. Solid phase microextraction, or SPME,* an adsorption/desorption technique developed at the University of Waterloo (Ontario, Canada), eliminates the need for solvents or complicated apparatus for concentrating volatile or nonvolatile compounds in liquid samples or headspace. SPME provides linear results over wide concentrations of analytes (1-4), is compatiblewith any packed column or capillary gas chromatograph or gas chromatograph-mass spectrometer system, and can be used with split/splitless or direct/packed injectors. An SPME/HPLC interface allows the technique to be combined with analysis by HPLC, expanding the applications for the extraction technique to detection of surfactants in water, pharmaceuticals in biological fluids, and many other analyses.

An analytical process typically consists of several discrete steps: sampling, sample preparation, separation, quantification and data analysis. For example, in the analysis of semivolatile components in water, the target analytes are first extracted into an organic solvent. The resulting solution is then introduced into an analytical instrument for separation, quantification, and possible identification. Each of these steps affects the precision, accuracy and speed of the analysis. Although multi-dimensional techniques such as gas chromatography/mass spectrometry (GC/MS) have improved separation and quantification, the preparation step is still time consuming and often uses a significant volume of organic. SPME was developed to simplify the preparation step. SPME is a microextraction technique, which means that the amount of extraction solvent is very small compared to the sample volume. As a result, exhaustive removal of analytes to the extracting phase does not occur, rather an equilibrium is reached between the sample matrix and the extracting phase. To make this approach practical, the extracting phase is...

References: 1. http://www.sciencedirect.com/science
2. www.geocities.com/hpgc/chem700/spmenotes.pdf
Appendix
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