High Surface Area Solid Phase Microextraction

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High surface solid phase microextraction (HSA-SPME) is an interesting extraction technique developed in 2009 which enhances the efficiency of classic SPME by increasing the total area of the extracting phase (1). The core of the classical HSA-SPME device is an oxidation-resistant metallic wire coated with a carboxen/polydimethyl siloxane film which is the responsible for analyte extraction. This metallic wire is wrapped around a borosilicate glass tube which is introduced in an outer glass tube where a gaseous sample flows in a controlled fashion (see Figure 1).
 
Figure 1. High surface solid phase microextraction device
HSA-SPME consists of two general steps. First of all, a gaseous sample is introduced into the device at a controlled flow and the analytes are retained in the SPME coating. Once the sampling has been completed, the target analytes are thermally desorbed applying an electric current to the metallic wire and further focused and preconcentrated on a microtrap for their subsequent analysis by gas chromatography.

In a recent article accepted for publication in Analytical Chemistry (2), HSA-SPME device is improved by introducing a type-K thermocoupled which permits a more precise temperature control on the unit. The new device has been applied to the determination of chemical warfare agents and degradation products at very low concentrations.

The authors compare the HSA-SPME with a conventional thermal desorption unit and the results show that HSA-SPME is superior when high volumes of samples are processed, that is, HSA-SPME provides higher peak areas per unit sampling times. In fact, subparts per billion by volume levels can be determined with only 15 s of sampling.

We strongly recommend these articles to our readers. The on-line combination of two HSA-SPME as well as the determination of warfare degradation products in clothes are quite interesting.

References:

(1) Directly Heated High Surface Area Solid Phase Microextraction Sampler for Rapid Field Forensic Analyses. Link to the article

(2) Application of a High Surface Area Solid-Phase Microextraction Air Sampling Device: Collection and Analysis of Chemical Warfare Agent Surrogate and Degradation Compounds. Link to the article

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