Solid phase microextraction
Encyclopedia
Solid-phase microextraction, or SPME, is a sample preparation technique used both in the laboratory and on-site. Developed in the early 1990s at the University of Waterloo
by Dr. Pawliszyn's group, it is a simple and inexpensive technique where the use of solvents is not necessary.
SPME can be thought of as a very short gas chromatography column turned inside out. SPME involves the use of a fiber coated with an extracting phase, that can be a liquid (polymer
) or a solid (sorbent
), which extracts different kinds of analyte
s (including both volatile
and non-volatile) from different kinds of media, that can be in liquid or gas phase. The quantity of analyte extracted by the fibre is proportional to its concentration in the sample as long as equilibrium
is reached or, in case of short time pre-equilibrium, with help of convection
or agitation. After extraction, the SPME fiber is transferred to the injection port of separating instruments, such as a Gas Chromatograph
, where desorption
of the analyte takes place and analysis is carried out.
The attraction of SPME is that the extraction is fast and simple and can be done usually without solvents, and detection limits can reach parts per trillion (ppt) levels for certain compounds. SPME also has great potential for field applications; on-site sampling can be done even by nonscientists without the need to have gas chromatography-mass spectrometry equipment at each location. When properly stored, samples can be analyzed days later in the laboratory without significant loss of volatiles.
University of Waterloo
The University of Waterloo is a comprehensive public university in the city of Waterloo, Ontario, Canada. The school was founded in 1957 by Drs. Gerry Hagey and Ira G. Needles, and has since grown to an institution of more than 30,000 students, faculty, and staff...
by Dr. Pawliszyn's group, it is a simple and inexpensive technique where the use of solvents is not necessary.
SPME can be thought of as a very short gas chromatography column turned inside out. SPME involves the use of a fiber coated with an extracting phase, that can be a liquid (polymer
Polymer
A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...
) or a solid (sorbent
Sorbent
A sorbent is a material used to absorb liquids or gases. Examples include:*A material similar to molecular sieve material. It has a large internal surface area and good thermal conductivity. It is typically supplied in pellets of 1 mm to 2 mm diameter and roughly 5 mm length or as...
), which extracts different kinds of analyte
Analyte
An analyte, or component , is a substance or chemical constituent that is of interest in an analytical procedure. Grammatically, it is important to note that experiments always seek to measure properties of analytes—and that analytes themselves can never be measured. For instance, one cannot...
s (including both volatile
Volatility (chemistry)
In chemistry and physics, volatility is the tendency of a substance to vaporize. Volatility is directly related to a substance's vapor pressure. At a given temperature, a substance with higher vapor pressure vaporizes more readily than a substance with a lower vapor pressure.The term is primarily...
and non-volatile) from different kinds of media, that can be in liquid or gas phase. The quantity of analyte extracted by the fibre is proportional to its concentration in the sample as long as equilibrium
Chemical equilibrium
In a chemical reaction, chemical equilibrium is the state in which the concentrations of the reactants and products have not yet changed with time. It occurs only in reversible reactions, and not in irreversible reactions. Usually, this state results when the forward reaction proceeds at the same...
is reached or, in case of short time pre-equilibrium, with help of convection
Convection
Convection is the movement of molecules within fluids and rheids. It cannot take place in solids, since neither bulk current flows nor significant diffusion can take place in solids....
or agitation. After extraction, the SPME fiber is transferred to the injection port of separating instruments, such as a Gas Chromatograph
Gas-liquid chromatography
Gas chromatography , is a common type of chromatography used in analytical chemistry for separating and analysing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture...
, where desorption
Desorption
Desorption is a phenomenon whereby a substance is released from or through a surface. The process is the opposite of sorption . This occurs in a system being in the state of sorption equilibrium between bulk phase and an adsorbing surface...
of the analyte takes place and analysis is carried out.
The attraction of SPME is that the extraction is fast and simple and can be done usually without solvents, and detection limits can reach parts per trillion (ppt) levels for certain compounds. SPME also has great potential for field applications; on-site sampling can be done even by nonscientists without the need to have gas chromatography-mass spectrometry equipment at each location. When properly stored, samples can be analyzed days later in the laboratory without significant loss of volatiles.
Books
- Pawliszyn J.: Handbook of Solid Phase Microextraction, Chemical Industry Press, 2009.
- Pawliszyn J.: Solid Phase Microextraction: Theory and Practice, Wiley-VCH, 1997.
- Pawliszyn J.: Applications of Solid Phase Microextraction, Royal Society of Chemistry, 1999.